Contrary to what you may have “learned” in the movie God’s Not Dead – atheists are not angry with God.
I’ve been a closet atheist for a LONG time – denying it even to myself until I came out recently. And it is simply because I do not find sufficient evidence to support me believing in ANY god. Nothing bad happens to turn someone into an atheist. I have been very pleased with my life overall. Has it been perfect, No! Has it been bad, NO!!!
I dated an agnostic / spiritual but not religious guy briefly and he was trying to pull away from his religious upbringing. I could tell that he had put a lot of thought into much of what he believed or didn’t believe, but one thing struck me as odd. He insisted that there must have been a specific point in time when I decided I was an atheist and that it would be linked to something that happened. But alas, that is not how it worked for me.