The existence of God can be rationally demonstrated and known with certainty (Aristotle, Aquinas, and other great thinkers show us this). But this knowledge is extremely difficult to reach. The existence of God is one of the final conclusions of metaphysics, and metaphysics itself requires one to first master other sciences such as natural philosophy. Hence, acquiring a demonstrative, scientific knowledge of the existence of God requires great discipline and strength of intellect.
However, there are many things which we are justified in believing even if we cannot have a scientific knowledge of it. Students of basic math trust that a certain equation is true without understanding why or how it is so. They do so because they accept what is taught to them by a competent authority, namely the teacher. But we can have a justified belief in God in a very similar way.
The purpose of all knowledge and activity is ultimately to help us live the good life. If we want to learn how to live the good life well, it is reasonable to look at the examples of those whom we take to have best exemplified what it is to live the good life, and then to model our own lives after them. This, I think, is something analogous to the example of the math teacher. A math teacher is a competent authority in math; and great human beings are competent authorities and masters in the art of living well. And just like a math student doesn’t have to fully comprehend a certain equation given to him in order to use it; so disciples of the great ones don’t have to fully comprehend what or why their masters do/teach in order to accept it and imitate it.
So, when I look at the examples of the great humans, those whom I perceive as living the good life and flourishing as humans as much as possible, I notice that a large number of them believed in the existence of God; and moreover that they held their belief in God to be directly relevant to their living the good life. To name a few: Jesus of Nazareth, St. Paul, Augustine, Thomas Aquinas, and pretty much all of the saints of the Church.
One might notice that all of the examples I’ve given are specifically Christian. And that’s on purpose, for at least two reasons: 1) I find the moral ideal of the Christian life to be the highest ethic ever taught to man; and 2) the Christian saints are people who actually lived out this high moral ideal to an incredible degree. These are significant contributing reasons to my own belief that Christianity is true.
There are certainly examples of great non-Christian heroes. People like Socrates, some of the stoics, the Buddha, etc. But still, the vast majority of these also held a belief in God, and considered that belief important to their living the good life.
It’s important to note what I’m not saying. I’m not claiming that atheists and those who don’t believe in God can’t be good or great humans. I’m also not making a moral argument, that the existence of objective moral values and duties requires the existence of God. Instead, I’m making a kind of pragmatic, existential argument for justified belief on the basis of competent authority. More formally, something like this:
- It is reasonable to accept the teachings of a competent authority, even without possessing full understanding
- The great human heroes are competent authorities on living the good life
- As I personally perceive it, the vast majority of the greatest human heroes have considered belief in God an important aspect in their living the good life. More specifically, I consider Jesus of Nazareth and the Christian saints to consistently be the highest exemplars of the good life
- Therefore, it is reasonable to accept belief in God as a component of trying to live the good life; and more specifically to accept the teachings of the Christian faith