Philosopher Edward Feser in The road from atheism explains his journey. He starts out:
As most of my readers probably know, I was an atheist for about a decade — roughly the 1990s, give or take. Occasionally I am asked how I came to reject atheism. I briefly addressed this in The Last Superstition. A longer answer, which I offer here, requires an account of the atheism I came to reject.
I was brought up Catholic, but lost whatever I had of the Faith by the time I was about 13 or 14. Hearing, from a non-Catholic relative, some of the stock anti-Catholic arguments for the first time — “That isn’t in the Bible!”, “This came from paganism!”, “Here’s what they did to people in the Middle Ages!”, etc. — I was mesmerized, and convinced, seemingly for good. Sola scriptura-based arguments are extremely impressive, until you come to realize that their basic premise — sola scriptura itself — has absolutely nothing to be said for it. Unfortunately it takes some people, like my younger self, a long time to see that. Such arguments can survive even the complete loss of religious belief, the anti-Catholic ghost that carries on beyond the death of the Protestant body, haunting the atheist who finds himself sounding like Martin Luther when debating his papist friends. . . .
. . . Speaking for myself, anyway, I can say this much. When I was an undergrad I came across the saying that learning a little philosophy leads you away from God, but learning a lot of philosophy leads you back. As a young man who had learned a little philosophy, I scoffed. But in later years and at least in my own case, I would come to see that it’s true.