Introduction to Catholic Theology

What we believe about God, why, and how it’s different from LDS (Mormon) beliefs

Before I begin, I must mention two things. First, though I write of Catholic theology, these are the beliefs of virtually all Christian denominations, Catholic and Protestant alike. For brevity and since I am in fact a Catholic, I will simply use the word “Catholic.” Second, in this article I follow very closely the model Frank J. Sheed used in his book Theology for Beginners (links will be at the end of the article). This was intentional, because his book is by far the simplest, clearest, and most concise explanation of divine truths I have ever seen. I must advise all my readers: read my article to see briefly the many important points where Catholic and LDS beliefs diverge, and to have the briefest of introductions to Catholic theology, then go obtain and read Theology for Beginners. I can’t recommend the book enough to those who seriously want to understand Catholic theology. Now, to business.

In a well-known story, St. Augustine tells of a day he walked along the beach pondering God. He saw a little boy scooping up water from the ocean and emptying it onto the sand. Incredulous, he asked the boy what he was doing. The boy answered that he was emptying the ocean onto the beach. Augustine told him it was impossible, and an angel told Augustine that the boy will have finished long before Augustine can exhaust everything that can be said about God.

The topic of God is infinitely deep. Things that God has revealed about Himself can be hard to fathom at first, and when by His gift we finally wrap our brain around them, new and deeper concepts arise for us to ponder. The pondering of theology is an eternally flowing fountain, a tree that ever bears fruit.

With that in mind, I want to say that this article is only an introduction. Theologians throughout the centuries, from Augustine himself, to St. Thomas Aquinas, to Peter Kreeft in our own day, have written much more detailed, enlightening, authoritative, precise, and beautiful works about God than this. This article is meant to introduce Catholic theology to Latter-day Saints, and to Catholics who don’t yet understand it either. It is meant to show contrast between the two faiths where many people have missed it. It is meant to build bridges and take away common misunderstandings. It’s very much a crash course; there is so much information that I’m afraid it doesn’t flow very well but is rather blunt. I apologize, but as I said, I wanted to make it something one could read as a brief introduction to Catholic theology and where it differs from LDS theology.

In this the most important of subjects, remember that I’m not an authority; I’m not a successor of the apostles in the fullest sense, I’ve had no formal training, and I’m relying only on my study, my short experience, and the guidance of the Holy Spirit not to make any errors in this work. If I have made errors, I’ll gladly and quickly correct them. Any deficiency is mine; all glory is God’s.


In my experience, one of the most common problems in dialogue with LDS is the existence of disconnects in our language. Certain words have had new meanings established for them in LDS theology, meanings very different from what the words have meant for perhaps the past couple of millennia. There are also terms that LDS and even Catholic Christians commonly misunderstand. I’ll do my best to define the Catholic understanding of such words in very clear terms and with as much explanation as possible to get their meaning across.


The first of the words I must define is mystery. Believers of every Christian faith often take the term to mean something that cannot be known, something on which attempts at deeper reflection are useless. The attitude can seem to be noble, viz., “We must simply accept it on faith. It’s a mystery; we have God’s word on it and our minds couldn’t possibly fathom it now.” It can also be a cop-out: “It’s a mystery. It can’t be explained.”

This is not at all the proper Catholic understanding of the word. In truth, a mystery is not something about which nothing can be known. It is something about which everything cannot be known. It turns the common understanding on its head: a mystery is ever profound, always fruitful, and we can understand as much as we are able, no matter how much we already understand. Understanding this is important, because I often hear from LDS that Christians believe in a remote, impersonal, unknowable God. Nothing could be further from the truth – we believe in a God so present, personal, and real that He can always be known as much as we can know Him (Rom. 11:33-34).

As I hinted in the introduction to this article, God is a mystery. Because of that fact, probably every tenet of the faith I mention in this article is a mystery. That means the reader can and should continue to learn and cogitate about whichever of the points has gotten his attention. I guarantee that volumes have been written about any of them, and as I said, in much more detail than I will use in this article. Thus I urge everyone for whom this article is a taste of the mystery of God: take your fill; drink as much as you can.

I. Spirit

Our examination begins with the concept of spirit. LDS teaching is that spirit is “more fine or pure” matter, and that all things are in fact matter (see Doctrine and Covenants 131:7-8). However, the traditional, Catholic meaning of the word is not so simple. I can’t think of a simpler definition than that spirit is that which knows and loves. Matter cannot do either, even animated matter like plants and animals. Even the most human-like of chimpanzees cannot know and love. These two actions are the faculties of a spirit alone.

Spirit has no parts. This is important but can be difficult to comprehend at first. On this subject, we must leave behind our imagination, because imagination is concerned only with images, things that can be seen. Spirit cannot be seen, and we must use only our intellect to learn about it. Returning to the subject, spirit has no parts. A part is an element of a being that is not the whole of it. Spirit is in no way at all divided – it is not a group of other elements; it is wholly itself. There is no top that isn’t the bottom or bottom that isn’t the top. It is not divided out into space, as matter is; a man’s spirit is not spread out through his body so that if he were to cut off a limb, he would lose some of his spirit. Again: spirit does not occupy space. Spirit is also immortal: it’s not subject to the decay that afflicts living material beings so that they age and die.

II. God, the infinite spirit

God has all the qualities of a spirit: He knows and loves, He has no parts, He does not occupy space, and He is immortal. The difference between Him and any other spiritual being is that He is infinite.

Infinity is another commonly misunderstood concept. “Infinite” means utterly without limit. In LDS writings, the word “infinite” is often used, but I have never seen it applied in its literal sense to a being. God is not infinite in LDS theology, but in Catholic theology, He is the only infinite being. The following three qualities of God will help demonstrate the differences and the meaning of “infinite.”

First, God is omnipotent (Rev. 19:6). He is almighty; powerful without any limit whatsoever. The most basic fact of our existence is that we do indeed exist. This is the greatest of limits to a being’s power; one would be powerless no matter what if one did not exist. We exist only because a number of other things allow us to: our parents, their parents, the environment, etc.; there are vast numbers of things that ultimately caused us to exist as we do. However, the same is true of everything in the universe: it is caused by something else. Everything is a created being, a receiver of existence from something else. But if nothing exists but created beings, how did any of it come to be in the first place? The only explanation is that there is one who gives existence.

God is the giver of existence. Ultimately He is the cause of everything else that is. He does not need to receive existence from another; He is able to give it because it’s in His nature to exist. He is existence. This is the meaning of self-existence. A being is self-existent if it is what it is entirely without limit, and without relying upon anything else to be what it is. In the “King Follett Discourse,” Joseph Smith described his notion of eternal spirits as “self-existent,” but in truth a finite being cannot be self-existent. A being contingent on anything else whatsoever can’t be self-existent. Only an infinite being is self-existent: it has no limit on its existence. God is that being.

This is the meaning of the name God gives us to call Him in the Old Testament, and which Jesus called Himself in the New Testament: “I AM.” (Exod. 3:14, John 8:58) God is the only being who can say “I AM” entirely without qualification. Finite beings such as ourselves can only say “I am, but only because…” and name whatever contributes to our existence, and whatever contributes to each contributor’s existence. In the end, God alone is the source. Because of this the highest of power (and, of course, because He has all other power), He is truly omnipotent.

Second, God is omnipresent (1 Kgs. 8:27, Eph. 4:6). In LDS theology this is taken to mean that His influence permeates the universe like the sun’s energy does our solar system. This is necessary because LDS believe that God’s actual presence is limited to a physical body. But the Catholic belief is that God is in everything. Now, since spirit does not occupy space, this cannot be true in the same sense that a fluid is present in a container. The way that spirit is in matter is made clear by our own spirits: it is present where it operates. My spirit is in my body, for it operates only in my body. It still does not occupy space: as mentioned before, it is not spread out evenly among my physical parts. God’s spirit is in everything because God operates in everything. If He didn’t operate in something, it wouldn’t exist.

Third, God is eternal. Here again is a source of confusion. While the LDS definition of “eternal” seems to depend on the context, the Catholic definition is “transcendent of time.” That is, to be eternal is not to exist in time at all. To understand this, we also must understand what time is (and few people do). Time is a measure of change. An hourglass in which no sand is changing position is an hourglass that’s not measuring time. To be divided out into time, i.e. to change, is an attribute only of finite beings. If I change once in my existence, then my existence is divided into two parts: the first is the part before the change, and the second is the part after the change. But if I never change at all, observing me would yield no sense of time. If nothing in existence ever changed, time would be utterly meaningless.

God is not finite, though. He possesses all of His existence at once. Just as He is not divided into parts in space, He is not divided into parts in time (Ps. 90:2). As the Scriptures tell us, God does not change. Looking at it from another angle, we also know that God is perfect. Yet if He changed, that would imply a lack of perfection. Either He lacked perfection and changed to go toward it, or He possessed perfection but changed away from it.

A couple of analogies can help us understand God’s transcendence of time. If I hold a book in my hands and read it, the flow of time in the book has nothing whatsoever to do with me. A thousand years may go by in the book, but it’s nothing to me, because I’m not a character in the book. I can peek into it at whatever point I want. Of course, the analogy breaks down because God is not a reader but an Author, but it helps to show how He is outside of the time in which His creation is bound up. Another analogy comes from C.S. Lewis. He said to draw a line on a piece of paper. The line represents time. We are somewhere on that line, and God is holding the paper in His hand. Again, this helps clarify how God is eternal.

These attributes of God, though they are certainly not the only ones, show us the difference between the infinite Being and His finite creations. The difference itself is unfathomable (Isa. 55:9).

III. Infinite actions

The difference between God and man also includes important differences in the way we employ the faculties we have in common. First, knowledge: the knowledge we possess at any moment is only a tiny portion of all the knowledge we ever possess in our existence. We learn new things and forget old things. We can only focus on one thing at time. We make mistakes. God doesn’t do any of these things. His knowledge is all present to Him at once (Heb. 4:13). Second, love: our love, too, is more or less transient. Our love can be ignited, increased, diminished, and extinguished. God’s love cannot; it is as perfect and limitless as He. Finally, power: in order to create, which is the highest of power, we need material to begin with. God does not. His almighty creative power requires absolutely nothing (Rom. 4:17).

Another important fact, alluded to above, is that God’s attributes are not distinct from Himself. This is not as difficult as it sounds. God’s knowledge, being perfect, is knowledge of absolutely everything, including Himself. If He had something that His knowledge did not, then it wouldn’t be perfect. His love is likewise.

IV. Person and nature: the Trinity

We come now to a doctrine often misunderstood by LDS and Christian alike: the Holy Trinity. Almost anyone can say that the Trinity is three Persons in one God, but I’ve met few who have any idea what that means. To understand it, we must understand person and nature.

Nature is what answers the question, “What is it?” Nature means what something is, what it can do, how it does it, of what it is made (if anything), and so on. It’s in a bird’s nature to fly, but not in a rock’s or a man’s. Both divine and human nature are capable of knowing and loving. God’s nature includes being infinite, but of course man’s nature does not.

Person is what answers the question, “Who is it?” It is a person who actually is of a nature, does the actions, and so on. A person possesses a nature; we say “my nature” but never “nature’s me.” A dog, a tree, and a rock are all beings with one nature but no persons; they are non-personal. A man is one nature possessed by one person; he is personal. God is one divine nature possessed by three divine Persons; He is tri-Personal.

That’s the doctrine of the Trinity: three Persons in one God. None of the three is either of the others; each is wholly Himself. Each one is God, but there is one God, not three. Each totally possesses the divine nature – it isn’t shared among them. The divine Persons are distinct, but not separate beings; if not for the nature they possess, no one could even exist (there will be more on this later).

Again, this may seem like nonsense, because of our knowledge mainly of personal and non-personal beings. But it can hardly be declared impossible; in reality we know very little about what a person is or what a nature is. If I am asked to tell about a person, I can communicate things about the person, but that’s not the same. The way to truly know a person is to love the person. Human nature is similarly mysterious. If the knowledge of a human nature or person is something we have such difficulty communicating, how much more the knowledge of the divine nature or a divine Person?

V. Three Persons: the life of the Trinity

What follows should help cast light on the mystery of the Trinity. We will first consider God the Father and God the Son.

Revelation tells us that Jesus is the only Son of God (John 3:16). What is a son? A son is a distinct person, alike in nature to his father. The father communicates his own nature: the son of a dog is a dog, the son of a human is a human, the Son of the only God is God. Revelation also tells us that Jesus is the Word who is with God, who is God, and by whom all things were made (John 1:1-3, 14). What is a word? A word is an idea that comes forth from the one who thinks it. We send forth words using our mouths, and they pass away as soon as they are spoken. God’s Word does not pass away (John tells us He was in the beginning with God), and God doesn’t have to use a mouth to form words and transmit them through matter as we do. But His Word is an idea, an idea of Himself.

Both a son and an idea of one’s self are likenesses of one’s self. Our ideas of ourselves are very imperfect. There are things we don’t realize about ourselves; there are misconceptions we have about ourselves; and we are constantly changing, so that we couldn’t completely know ourselves at any rate. But God has no such limits. God’s knowledge of Himself is perfect. This idea, or image, that God has of Himself is God Himself – and has been revealed to us as the Son.

The Father is omnipotent, omnipresent, eternal, etc., and so His image is as well, else His knowledge of Himself would be imperfect. The Father knows and loves, and so His image knows and loves; in other words, His image is a Person. Whatever is in the Father is in the Son (John 16:15). Note: an idea is distinct from, but not separate from, the thinker; it couldn’t wander off on its own. So too, the Son is distinct from the Father, but would not exist without the Father.

Along the same lines, we must remember that God is not bound by time as we are, and so it’s not as though the Son came after the Father. To help with understanding this, think of a book on a desk. The desk has a causal relationship with the book: it causes it not to fall to the floor. But it’s not as though the desk makes some exertion and then the book is held up. As long as the desk is there, the book doesn’t fall. So with the Father and the Son. God’s very nature includes both; if the Father is there, so too is the Son.

It would be difficult to list all of the ways in which LDS theology diverges from traditional Catholic Christianity the nature of the Father and the Son. To name a few: LDS teach that the Father and the Son are both the same kind of being as we are, but they have reached godhood while we haven’t yet; the Catholic belief is that both Father and Son are God, and God and the difference between them is an infinite gap able to be bridged only by God Himself (more on that later). LDS believe that by nature the Father and the Son have physical bodies; Catholics believe that God by nature is spiritual and not limited to a body. LDS say that God is the Father not only of Jesus but of all of us in the same way, and that Jesus is our oldest “spirit brother,” while Catholicism holds that the Son is the Father’s only-begotten by nature, but we can be made His children (more on that later as well). LDS founder Joseph Smith taught that the Bible had been altered from its original form, and claimed to have re-translated it by divine power. John 1 was one of the books he said was changed, and in his re-translated version, there was no more reference to the Word being God. Catholics, on the other hand, know that the Scriptures are reliable, as the Church has preserved them from the earliest days to the present. LDS believe that the Son is “Jehovah” (the King James Bible’s poor transliteration of the Hebrew YHWH) and the Father is “Elohim,” both as referred to in the Old Testament; Catholics know it’s the same God. The list could go on (and does, in other websites and articles), but we will move on for now.

Next, God the Holy Spirit. Thus far, we might imagine God as a bit of an odd being, eternally occupied with knowing Himself. But the inner life of the Trinity, shadowed in the Old Testament and revealed by Christ in the New, includes not only knowledge but the other spiritual faculty, love. Consider that Jesus tells us the Spirit is a “he,” not an “it” (John 14:16, 26) – the Spirit is a Person. A finite being’s idea of himself is not a person. A man can know his self-image but it cannot know him. He can love it and admire it, but it cannot love him back. However, God’s self-image is a Person. He can and does love His self-image, and His Son loves Him in return. As both Father and Son are co-eternal, this interflow of love is also eternal. The expression of their love for each other is the third divine Person, the Holy Spirit. Love is a gift of one’s self. Father and Son love each other perfectly; they hold nothing back. Their gift is no less than they are, God Himself.

This is in stark contrast to LDS teaching that the Holy Ghost (as they prefer to call Him) is another spirit child of the Father, another sibling of ours. LDS belief is that the Holy Ghost has not yet received a physical body as Jesus and the Father have; He is voluntarily waiting so that He can perform tasks (such as indwelling believes) that corporeal beings cannot. However, LDS prophetic teaching also includes that the Spirit cannot be in more than one place (which would be correct, if spirit were merely a higher form of matter). Catholic Christianity knows that the Holy Spirit is, in fact, the same God, no less or more, and with all the attributes of God.

We say that the Son is begotten of the Father, not in the same way that human fathers beget sons, but eternally – “God from God, Light from Light, true God from true God, begotten, not made, one in being with the Father.” We know that the Father does not come first, or somehow wait for a while before begetting the Son. Both are part of God’s nature. So too is the Holy Spirit, “who proceeds from the Father and the Son.” Father and Son do not have to wait to love each other, or have to wait for their love to build up before it becomes a Person. The Spirit exists co-eternally with the Father and the Son.

To avoid any confusion, I’ll mention the appropriation used in Christianity. In general the Father is referred to as the Creator, the Son as the Redeemer, and the Holy Spirit as the Sanctifier. This is not to say that each acted alone – in all divine operations, all three Persons are at work. However, we appropriate tasks to each Person to help us keep their distinction in mind. We call the Father the Creator because He is the Origin, who begets the Son, from whom along with Him the Spirit proceeds. We call the Spirit the Sanctifier because the gifts He gives us are gifts of love. We call the Son the Redeemer because it is He who became man to redeem us – again, more on this will follow later.

VI. The existence of man

Briefly, we will examine the reason that God created beings, including man, from nothing. LDS believe that all personal beings are in some sense self-existent; they exist for an infinite time into the past and are made by existing gods into humans, then gods themselves. LDS belief is that this is the purpose of all who exist – to have spirit children in eternal families, and to glorify one’s heavenly parents. But this is incompatible with the historic, Catholic belief, that God is the source of everything that exists, rather than being an infinitesimal part of an existence with no apparent source. We know God’s perfection is complete; He knows infinitely the only being that could be known infinitely (Himself) and He loves infinitely the only being that could be loved infinitely (Himself). His spiritual faculties are infinitely active in this way, and infinitely satisfied. If He needed anything else, He would be imperfect. He need not have created at all.

Then why does He will other beings to exist? The answer is quite simply because other beings could enjoy His perfect existence as well, and so in His infinite goodness He wills them to exist for that purpose. He did not create us because He knew He could enjoy it. He created us because He knew we could enjoy it. We exist not for God’s sake but for our own, and we were created so that we could share His life. That is our purpose, that is our goal, and everything that gives us happiness is what is oriented to that goal, God Himself.

Note that He created beings of spirit only, the angels (who LDS believe are men who are not yet gods). For brevity, we won’t discuss angels. He created beings of matter only, like inanimate objects, plants, animals, etc. He also created beings of both matter and spirit, i.e., humans. We are unique in this sense; we are the union of the spiritual and material world.

Note also that He created man in His image. LDS believe that means that God has a physical, humanoid body, but Catholicism believes that it means we are spiritual beings, capable of knowing and loving, as He is. We know with our intellect and love with our will. The will, as both faiths agree, is free to choose to love God or reject Him. To reject Him is sin.

VII. The Incarnation

To be extremely brief, we Catholics believe that all of humanity is one race, or better yet, one family. We believe we were all represented as one by our common parents, Adam and Eve. We believe that their sin broke the entire human family from God (Rom. 5:12), making it impossible for them to share His life forever unless the gap was somehow bridged.

God’s love for us is so unutterably deep that He did this. He did it by becoming a man Himself, entering the finite universe He created, as one of its members. It is absolutely, entirely, infinitely beneath God to do this; it is the epitome of humility, yet for love of us He did it (Phil. 2:6-11). Thus, the Incarnation has profound meaning for Catholic Christians; we don’t believe that Jesus should have become a man in the natural course of things anyway. LDS do believe that it was a decision of Jesus to descend and redeem us, but they’re at a loss as to whether He would have been required to go through mortality, as everyone else in existence is, had we not needed redemption.

Anyway, the Incarnation means that God became man (John 1:14). The second Person did this, and to see why, we call to mind our idea of appropriation of divine actions. God created the universe, but it is not disordered chaos. Its order and design is evident in everything, the mark of great wisdom. However, by our sin we threw things out of order in our universe. The Son is the wisdom of the Father, and so it is He who restores it by becoming one of us.

Of course, the Son never ceased to possess the divine nature. There is not a time (nor can there be in eternity; it would be nonsense) when the Son stopped being God. Nor was there a time before the Incarnation when He wasn’t man, and after which He was. Rather, as part of the eternal action that includes creating and sustaining our universe, He enters it as one of us, taking a human nature as His own. So He is one divine Person (the Son) with two natures (human and divine). He is true God and true man. As such, He is able to reunite mankind with God. He is our representative, the new Adam whose sacrifice atones for all sin. By His Incarnation, life, death, and resurrection, which He did for each of us personally, we can again be united with God forever.

Nor did all of this happen in a vacuum. For the sake of men He became man, and He ministered among men. After His death they carried on His work, having been given authority in a great commission (Matt. 28:18-20). He united Himself with the human family by becoming man. Adam and Eve give us our natural life, born into sin, but Jesus gives us new life, born again into grace (John 3:3). Those who receive His life-giving grace are His body, the Church, whom He loves as a spouse (Eph. 5:23-30).

The Church spread as rapidly and vibrantly as wildfire, led first by the Apostles and then by their chosen leaders. The New Testament and documents from the time show us that the Church has been faithfully preaching the faith once for all delivered to the saints (Jude 3) since her birth, and will continue to do so for all time. In this manner God has deigned to work through men to bring them to Himself, as He did in the Old Testament, but this time built on Jesus Christ, the perfect, complete image and revelation of God (Col. 1:15). The Church is His body, with Him as its head, and it will never fail (Matt. 16:18, Eph. 3:21).


All I really want to say in conclusion is that much was left out of this article. Each item would yield a lifetime of fruitful meditation, and as I said, many if not most writings are better than this. Everything in this article I learned from great sources such as Frank Sheed, C.S. Lewis, the Catechism of the Catholic Church, and innumerable others I’ve studied. If the article was good, it’s because those sources are good. My only hope was to make a useful introduction for LDS or for Catholic Christians who are unaware of the important core differences in theology. So again, I exhort the reader to study, especially, as I mentioned before, Frank Sheed’s book Theology for Beginners, and/or for a more detailed treatment, Theology and Sanity. C.S. Lewis’s Mere Christianity is also solid gold. Many philosophical arguments for Catholic doctrine are made available in The Handbook of Christian Apologetics by Peter Kreeft and Ronald K. Tacelli.

A famous saying attributed to various saints goes something like, “Work like everything depends on you; pray like everything depends on God.” That’s the other side of my exhortation: study, but also pray. Not necessarily for direct, personal revelation, as LDS missionaries exhort potential converts, but pray for God to instruct you in whatever way He sees fit. It may be through learning more about Catholic teaching. It may be through other ways. But give these things the thorough pondering that they deserve, and pray to the Spirit for guidance, and love God with all your heart, mind, soul, and strength (Mark 12:29-30).

Related Links

Theology for Beginners

Theology and Sanity

Mere Christianity

The Handbook of Christian Apologetics

See also the Resources page for some links to excellent, relevant articles by Dave Armstrong.

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