You believe whatever you want, honey. That's the good thing about belief; each person is free to do it as they see fit.
Most atheists are agnostic atheists. We simply live our lives as if there are no gods, goddesses or other deities, until any evidence of their existence emerges.
I didn't convince myself that I am an atheist. Religion just made less and less sense, the more I learned about it, until there was simply nothing left. It was a little bereavement to me, realizing that there probably is no heaven where we can meet our loved ones. I used to like going to church at weddings, christenings and confirmations. Last time, I just felt empty; even singing the hymn made me almost cry. So no, it's not about what HAS to be true, or WINNING, or to CONVINCE ourselves. It's just a lack of belief in gods, goddesses and other deities.