Here is a quote by John Haught, taken from an interview with Amy Edelstein:
Sometimes people ask, “What is the evidence that the infinite exists?” For Augustine and for many religious people throughout the ages, the best evidence is the utter restlessness of the human heart. You could extend that also to the restlessness of the intellect itself. We all realize that no matter how much we know, there is yet more to be known; we all realize that no matter how much we get in life, how much we have, how much we possess, we are never fully filled up by it. So there is, in a sense, a God-shaped hole at the heart of our being. That’s what Augustine was saying—our hearts are restless until we rest in the infinite.