It is relatively safe to assume that if you’re reading this reflection, you likely believe in the existence of God. However, it is a very sad reality in our world today that many people do not believe in God. Some people equate belief in God and faith as fairy tales, mythology, or simply things we’ve made up to make ourselves feel better or less alone in the world. It is also sometimes misunderstood that faith and human reason cannot co-exist, but nothing could be further from the truth. Our human reason can, in fact, lead us to the truth which is then magnified by our faith.

The Catechism of the Catholic Church tells us that the desire for God is written on every human heart (CCC #27). We can see this in every person we encounter, whether they believe in God or not, and regardless of which religion or spirituality they practice (CCC #28). Everyone, in some way or another, is seeking truth and the meaning of life, however wayward it may seem to others. This is all driven by the desire God wrote into humanity to seek Him out, which is all largely rooted in our human reason.

One of the greatest theologians of all time is St. Thomas Aquinas (1224-1274). One of the things that made him so great was the way he used reason to get to the bottom of things pertaining to matters of God and of faith. He left behind volumes of his written philosophical and scholastic works which we still use regularly today. Today we will look at St. Thomas’ five proofs or ways for the existence of God.

The First Way – An Unmoved Mover

St. Thomas observes that the world is in constant motion. His definition of motion is broad and includes change in any object, inanimate or animate. So, people, plants, and animals constantly grow and change, but so do other things. The tree becomes the chair you’re sitting in and that chair becomes worn and tattered and then will eventually break and perhaps become firewood, later turning to ash. A puddle can grow or shrink depending on whether or not it continues to rain or the sun comes out. Whatever the example, all of creation is in motion. However, nothing changes by itself without something else causing the change. The flower grows because it receives proper nourishment from somewhere else. The chair changes because you sit on it regularly. As we attempt to go back and follow the chain reaction of motion and change, it cannot reasonably go back infinitely. There has to be an unchangeable first mover to start the whole thing in motion which St. Thomas calls God.

The Second Way – The First Cause

Everything in existence was caused by something else and did not just appear out of thin air. This is the cause-and-effect way in which the universe operates. A seed becomes a plant, but the seed was caused by a previous plant and so on and so forth. The chair was caused by a carpenter making it. The same is true for people and for animals. Nothing in existence comes about by its own doing. Again, we cannot follow causation backward infinitely. There has to be an uncaused cause after which everything else comes, which St. Thomas calls God.

The Third Way – Contingency or Necessary Being

It is not necessary for anything in the world to exist at all. Anything animate or inanimate in the world can cease to exist at any time, whether by death or destruction. When something stops existing, the rest of the world keeps going. It is also true that nothing and no one exists forever. This would mean that in any point in time, it could be possible that all unnecessary things could go out of existence, but that has not happened. Therefore, there is a necessary being on which the existence of things is contingent, or dependent. In other words, the reason the world hasn’t just vanished by now is because God, the one necessary being, continues to hold it in existence.

The Fourth Way – Gradation

This is my personal favorite of St. Thomas’ proofs for the existence of God. Everywhere around us we see gradation in the world, or a spectrum on which things exist. Things can be more or less good, more or less true, or more or less beautiful. You may think one painting is more beautiful than another. You may think one statement to be more or less factual than another. Perhaps you are making a choice and think one choice is better than another. Regardless of how each of us as individuals see that scale or gradation, there is a scale of good, better, and best. Like some of the other proofs, this scale cannot go on infinitely. Something has to be the standard by which we judge all other things. So there must be something which is perfectly good, perfectly true, and perfectly beautiful. That standard by which everything else is judged is God.

The Fifth Way – Design

St. Thomas observed that there is an intelligent design to the way the world works, particularly in the forces of nature and science. Gravity, magnetism, weather, wildlife, etc. all have a very precise way of working and a specific function in the way the world works. However, these things, in and of themselves, lack the intelligence to operate the way they do. In other words, a magnet is drawn toward your refrigerator, but it lacks the intelligence to know that it should be drawn. For all of this intelligent design to happen completely at random was impossible for St. Thomas to accept. Just as an arrow needs an archer to reach its target, the world needs an intelligent designer for everything to work properly.

These are the five proofs of the existence of God according to St. Thomas Aquinas. Of course, they have been argued against by anti-Christian philosophers and others for centuries. This shouldn’t be worrisome though, since everyone is on a quest for the truth because the desire is written on each person’s heart. While you may struggle with one or more of the proofs, can you identify one or two that really resonate with your sense of reason in accepting the truth of the existence of God? Perhaps you had a merely childlike trust and faith in the existence of God in your heart, but now feel more certain in your mind. Spend time in prayer and ask God to show you in concrete ways that He, in fact, exists.

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