How do we know that God exists?

The Bible teaches that God exists, and this is the one of the central commitments of the teaching of Jesus Christ. But many people these days do not believe in God, or at the very last they find it hard to believe. Why does Christianity teach that God is real? How do we know this?

Many people have confused ideas about God. They think that God is some particular thing “out there” in the universe somewhere. There is a story about the Soviet cosmonaut Yuri Gagarin, the first person to go to outer space. Some people allege that when he went out into space, he commented: “I don’t see any God up here.” It’s not obvious whether the story is true or not, but in any case it is a rather silly comment to make. Christians do not believe that God is some celestial being hiding out somewhere in outer space! Indeed, they do not think that God is merely one more thing among all the things that exist and that can be encountered in experience. The Christian idea of God is very different.

There are two ways we can come to know the existence of God. They have different starting points, but they end up in the same place. In a word, God is that from which everything else gets its existence and life. God is the source of everything. As we say when we recite the Nicene Creed, God the Father almighty is the maker of heaven and earth and of all things visible and invisible. But how do we know that there is a God? It is actually not hard at all to show this.

It is important to start with a distinction. All the things we encounter in our experiences have various qualities that they define them. For example, I have two noteworthy qualities: first, I possess the capacity to learn language; second, I possess actual knowledge of the English language. These are two qualities that I have. At the same, I do not possess these qualities in exactly the same way. My capacity for learning language is a property that I possess in a normal and natural way simply in virtue of being a human being. That’s what it means to be a human, assuming that nothing else is wrong with me: I am capable of learning language. It may be easier or harder for me than for other people, but any normal human being possesses the capacity to learn language. At the same time, I do not possess knowledge of the English language in this same way. I wasn’t born with it, after all! There was a time when I didn’t know English, namely when I was a baby. Furthermore, there are plenty of other human beings who do not know English. This means that being a human is not sufficient for possessing knowledge of English. If any one is going to possess knowledge of the English language, they will have to receive it somehow from outside of themselves, namely from someone who already knows the language.

Thus, we can make a distinction between two ways things possess their qualities. A thing possesses a quality in an original way if it has that quality just in virtue of what kind of a thing it is, and it possesses a quality in a derivative way if it has it in virtue of something else outside of it. I possess the capacity to learn language in an original way, since I have this quality in virtue of being what I am, namely a human being. But I possess knowledge of the English language in a derivative way, since I have this quality in virtue of things outside of me, such as my parents and my teachers at school.

Now, it is obvious that nothing can possess a quality in a derivative way unless something else possesses that quality (or some related quality) in an original way. For example, I could never learn English if no one else on Earth knew English! There must be someone who already knows the language and can teach me it if I am to know it myself in a derivative way. Consider also the following example. The moon at night is illuminated. But the moon is not originally luminous! It does not produce light on its own. Rather, it receives its light from the sun, which is originally luminous. And if there were nothing originally luminous, if there were nothing luminous simply in virtue of what it is, then the moon itself could never be luminous in its own derivative way.

In this way, we can see why God must exist. What is God? God is that which exists in an original way, simply in virtue of what He is. It is obvious that nothing we find in the world exists in an original way. None of us have always existed, for example, but rather we began to exist at a certain point in time. The planet Earth, too, did not always exist, but rather began to exist at some point in time. Furthermore, for any of the things we encounter in the world, we could easily imagine that it does not exist. There is no contradiction in saying that I might not exist, or that cats do not exist, or that there be no solar system, no stars, no planets, and so on. All these things exist in a derivative way. They exist, but they do not exist simply in virtue of what they are. But, as I said earlier, nothing can possess a quality in a derivative way unless there is something that exists in an original way. This means that there must be something which exists originally, simply in virtue of what it is and not in virtue of anything else. This is what Christians refer to when they speak about “God” — that which exists originally, that in virtue of which everything else exists, the source of all existence.

Some people might think, “Maybe there is no God. Maybe the whole history of the universe is just one thing causing another thing to exist and then going out of existence itself. Maybe there is no original existing thing, just an infinite chain of derivatively existing things.” But this scenario is in fact impossible. There could be as many moons as you like. Without a sun, they will never be luminous. Consider also the following example. Suppose you are cooking beans in a pot while camping. The beans are not originally hot; they did not come out of the ground hot. They have to be made hot by something else. What makes them to be hot? Obviously the pot. But the pot is not originally, either! The pot wasn’t hot when you bought it at the store! This means that there must be something else making the pot to be hot, so that it can heat up the beans. But clearly this problem will not be solved by merely adding more pots! Even if you had an infinity of pots, each one within a bigger one, you would never be able to heat up the beans. What you need is something that is hot in an original and not derivative way. What you need is not more pots, but rather fire. And if there were no fire, if there were nothing originally hot, then the pot and the beans could not be made hot in a derivative way. So also, we cannot say that all the things that exist derivatively are merely caused by other derivatively existing things. There must be an original existing thing, something that exists simply in virtue of what it is — and that is what we mean when we talk about God.

Considered in this way, God is like the “foundation” of reality. Consider the analogy of a building. Can you have a second floor of a building without a foundation? Clearly not! It is impossible to build a second floor unless you have a foundation on which to place a first floor. In the same way, God is the foundation of reality. Everything else that exists — you, me, cats, dogs, horses, the planet Earth, and everything within the universe — can only exist in a derivative way on the foundation that is God.

This is one way to understand how it is that God exists. This way started from “outside” ourselves. We noticed a distinction between the ways things outside us can possess their various qualities, and we quickly saw that there must be something which exists in an original way. But it is also possible to discover the existence of God by looking “within” us.

You are alive right now. What does it mean to be alive? It means to experience yourself. You feel yourself to be alive in various ways: you feel happy or sad, you are aware that you are thinking of this or that, you notice that you see or taste or smell things, and so on. You are constantly experiencing yourself, and that is what it means to be alive. But did you do anything to be alive? Is the fact that you are alive right now a result of anything you’ve chosen to do? Obviously not! You simply are alive, even though your being alive is not a result of anything you’ve done. On the other hand, neither is there anything you can do to ensure that you stay alive for even one more second! After all, you have to first be alive in order to do anything! So you are alive, and this life that you possess is the condition of everything you experience or do, but your being alive is not your own accomplishment, nor can you do anything to secure even a moment’s more life for yourself. You are alive, but you are not alive in an original way. This Life that you feel within yourself, over which you have no control, which makes you to be alive even apart from your wanting it — that Life is God! God is that Life you feel on which you depend every moment of your life.

The Bible calls God “the living God” (Ps. 42:2). It says that “in Him we live and move and have our being” (Acts 17:28). This Life on which we all depend at every moment, which makes us to be alive, is God. This means that God is not far from us at all. He is as close to us as can be! We are constantly experiencing God as that Life which makes us to be alive and makes it possible to enjoy the good things of this world. This God also creates the entire world and sustains in it existence. We are surrounded by God on all sides, both outside us and within us! He is all around us!