I was brought up with Christianity...
However, there were some contradictions between the love of God and Hell when I read the Bible; it was a long process of doubt. But the process from theism to atheism was too short
1. I was Theist: I loved God (an insane love) and my best friend was Jesus (that hippie, LOL).
2. I was Deist: I didn't love God, but I was looking for an answer of tthe beginning of Earth and other things like that. God did it!!
3. I was Agnostic: I doubted about God, but I couldn't imagine a world without God. How the universe began?
4. I am Atheist: I studied about Darwin and the big Bang theory. I learnt the meaning of "theory" as a scientific explanation instead of a hypothesis!! I am happy. I enjoy my life.
However, I believe that god doesn't exist! I'm not sure that God doesn't exist!! If I am sure, I have to prove it, and it is impossible!!
There is no need to prove that god does not exist, as no proof exists that god does exist. Until they show me an ancient dry cleaning receipt with Jesus' name on it, I won't lend any credence to their tale.
I don't think there could be any "evidence" for god because anything physical would have necessarily arisen from the material world. If science can discover it, then it's probably not supernatural (but that doesn't mean it's not amazing!).
I think only god could prove god exists. And the fact that god hasn't, at least not to me, gives me a big clue that god isn't there.