Growing up I thought questioning God’s existence was off-limits. I assumed that even wondering how we can know God exists might in some way offend God. Aren’t we just supposed to believe? Many atheists believe that is exactly what theists do—believe in God out of blind faith without any good evidence or reasons to do so.
I soon discovered, however, that not only is it okay to ask questions about God’s existence, but that some of the greatest minds in history, many of whom were devoutly religious, have been meticulously exploring such questions for centuries. “Does God exist?” is the most fundamental question all truth seekers must wrestle with. Using reason alone apart from any religious truth claims, here are three classic arguments for God’s existence.
Introduced by Muslim philosophers in the Middle Ages, this first argument gains further evidence in its support from modern science. The basic structure of the argument is laid out below. The syllogism starts with two premises and ends with a conclusion, which logically follows from the premises.
Let’s start with the first premise: Everything that begins to exist has a cause. This is simple enough. We don’t see kittens or bananas popping into existence out of nowhere. The only thing that comes from nothing is nothing. If something begins to exist, something else caused it to come into existence.
The second premise is: The universe began to exist. This is strongly attested to by modern science, but that was not always the case. However, in 1927 theoretical physicist and Catholic priest Father Lemaitre proposed a theory that asserted the universe came into existence from an incredibly dense point, rapidly expanded, and is still expanding today. Interestingly, this idea was ridiculed by an atheist cosmologist who dubbed it the “Big Bang” theory in hopes to discredit it. For until this theory was accepted by the scientific community, it was commonly thought that the universe had always existed. Therefore, it was often thought, the need for a cause (especially a divine cause) of the universe was unnecessary. Now, the question is not whether the universe began to exist, but what caused it to come into existence?
If the first two premises are correct, that everything that begins to exist has a cause and the universe began to exist, then it follows necessarily that the universe has a cause. What is the cause?
We can start in the right direction by a process of elimination. The universe could not have caused its own existence. (It is important to note that the universe did not appear in an empty vacuum, for a vacuum assumes space already existed. With the start of the universe, space was one of the things that was created.) Before the universe began to exist, there was no space, time, or matter. And since the only thing that comes from nothing is nothing, something must have caused the universe to exist. Therefore, since the universe contains all matter, space, and time, the cause must be immaterial, spaceless, and outside of time. In addition, the cause must be powerful enough to create the universe out of nothing.
So what is this eternally (since it is outside of time) powerful cause? Perhaps it is not God but an impersonal force. The problem with this option is that an impersonal force cannot choose. Since the universe did not exist eternally but came into existence a finite time in the past, something with will power must have chosen to create the universe. The universe did not have to exist. But there is a universe, and it began to exist because something, or someone, with choosing power willed it into existence.
This leaves us with an all-powerful personal mind, for only a mind can choose. We can thus conclude that the cause of the universe is an immaterial, spaceless, timeless, all-powerful intellect or mind. The best option that fits that description is God.
This is one of my favorites because it’s intuitive and undeniably practical while being just as logical as other arguments for God’s existence.
Objective moral facts exist. We know this instinctively and (thankfully!) almost no one denies it. For example, imagine you are leaving the grocery store and see a man snatch a little girl from her mother’s arms, throw her into an unmarked van, and speed away while the mother screams and runs after her kidnapped daughter. You don’t pause and wonder what an interesting reaction the mother is having to someone else’s free choice—you call the police! That is because we know kidnapping is wrong. But the only reason this is wrong is because there is an objective moral order based on God’s existence.
If atheism were true and there is no God, there would be no such thing as objective moral facts. Child abuse, sex trafficking, rape, and murder would all be a matter of personal preference and social conditioning as part of the evolutionary process. If a lion forcefully copulates with a female, we would not accuse it of rape. Animals act on instinct and their actions have no moral value. But if we are just more evolved animals, then there is no objective moral basis for our actions either. We are just another species of animal made up of the same elements and will all soon return to lifeless carbon matter, just like a dead lion, toad, or slug. Without God, there is no such thing as good or bad. Everything, including ourselves and our actions, is simply the meaningless byproduct of random chemical reactions.
Therefore, because objective moral facts exist, God exists. Kidnapping a child from a grocery store parking lot is really and absolutely wrong. It doesn’t matter what the kidnapper thinks or what the prevailing laws are in his country. We know this. The only reason why we know this is because there is an objective moral order grounded in God’s existence.
This third argument is perhaps most well-known as one of St. Thomas Aquinas’s five proofs for the existence of God. Aquinas, a Dominican friar who lived in the thirteenth century, is widely considered one of the greatest philosophers and theologians of all time. The contingency argument goes something like this.
The world is filled with contingent beings, that is, beings that do not need to exist. I exist, but I did not need to exist, and the cause of my being is outside of myself. I can point to the cause of my existence as my parents, but they also did not need to exist just as their parents did not need to exist. This continues back all generations. And the same is true with everything we encounter in the world. Everything we see did not need to exist, and the cause of its existence is found outside of itself.
But this cannot go on infinitely back in time. For if there are only contingent, non-necessary beings, there would be nothing outside of these contingent, non-necessary beings to cause their existence. But contingent beings exist. Therefore, there must be a necessary being that caused the existence of all contingent beings.
Unlike a contingent being, this necessary being does not point outside of itself for its existence but is something that points only to itself for its existence. It is necessary in that it cannot be distinguished between what it is and that it is. A necessary being is a being that must exist by its very nature. Contingent beings and everything in the material world are not like this. Therefore, this necessary being must be something outside of matter and time which are bound by the universe. This necessary being has always existed and cannot not exist. It is existence itself. In the words of Aquinas, this is what we call God.
One could easily think of many bad arguments for God’s existence. For example, imagine a friend tells you “I won the jackpot after going to church, therefore God must exist.” All we can conclude from that is that your friend better buy you lunch and that this latest trip to the casino hasn’t helped your friend’s critical thinking skills. Of course, winning the lottery could have been total luck and likely did not involve any divine intervention.
But there are also many good arguments for God’s existence. Here I have summarized three that I find particularly helpful. Not all objections to these arguments were addressed, which would be impossible in a short article, and much more could be said. My hope is that this introduction to a few arguments for God’s existence will spark new questions and prompt further study.
