Does God exist? For Catholics, the answer to this question is ultimately a matter of faith. However, not everyone in the world shares this faith. So how are believers to argue for the existence of God when entering into dialogue with non-believers? A good place to begin is by looking back to a few of the more famous arguments put forward in favor of the existence of God. You will notice that each attempts to appeal to human reason, an approach that the Church approves of for it offers the possibility of encountering a starting point for discussion with non-believers. The Church is able to do this because, while faith certainly cannot be reduced to reason, faith is reasonable.

Look for the designer label

This argument is called the argument from design, or the teleological argument. It is one of the most ancient arguments for the existence of God, predating Christianity. The argument is grounded in the word “telos,” which means purpose or goal. The basic idea is that in order for something to have a purpose a “purpose giver” must exist. One common example used to illustrate this point is that of a clock. A clock has a purpose and is complex. It is definitely not something that spontaneously is created. A clock implies a clockmaker, or a designer. What’s more, the greater the design, the greater the designer. So, the universe, which clearly shows the marks of design and great complexity, would require a designer greater than itself, that is, a supernatural designer.

The theleological argument is still compelling today in large part because of the discoveries of science. Consider the following: a single strand of DNA is equal to one volume of the Encyclopedia Britannica; the human brain has approximately 10 billion gigabytes of capacity; and a single-celled bacteria is so complex that its survival depends on all its parts working together at the same time. All of this complexity presents a strong case against creation and design by mere chance.

Take it to the limit

St. Anselm (1033-1109) gives us this next argument, which is also known as the argument from being, or the ontological argument. Interestingly, this argument was the fruit of Anselm’s unsuccessful grasping for a single proof of God. When he finally reached exhaustion, he was given a name: that than which no greater can be thought.

From there he reasoned, if God exists only in the mind, then something greater can be thought of, i.e. that God exists both in the mind and in reality. Consequently, God must exist, for to exist in the mind and reality is greater than to exist only in the mind. In a like manner, though we are imperfect beings, we can conceive of a perfect being, which we call God, for perfection is that than which no greater can be thought. Thus, if God is not perfect, God could not exist, and if God did not exist, God would not be God.

Poetry in motion

St. Thomas Aquinas actually offers us five arguments for the existence of God; the first argument has been the most influential. Borrowing from Aristotle, Aquinas begins with the observation that it is evident from the senses that some things are in motion, or changing. He then notes that nothing moves itself. Motion is a transformation from potential to actual and something cannot be in a state of potential and act at the same time. Yet, what is producing the change must also be acted upon for the same reason. Now, there cannot be an infinite regression of “moved movers,” so there must exist a first “unmoved mover.” This “unmoved mover,” or pure action, is understood to be God.

Place your bets

Finally, we have French philosopher Blaise Pascal (1623-62) and his famous wager. Pascal argues either God exists or God does not exist. There is no other option and these are mutually exclusive, that is, God cannot both exist and not exist. What this means is that we have to decide whether we are going to bet for or against the existence of God. This is our only choice.

Pascal continues by arguing that the winning bet is on the existence of God. He reasons that we have everything to gain by living our lives as though God exists and living in accord with that belief. Then, if at our death we find that there really isn’t a God, we will have still won because we would have led a virtuous Christian life. In contrast, if we bet on the non-existence of God and live in accord with that belief only to find out there really is a God, we will have lost in the ultimate sense of the word.