My parents baptized me into the Catholic church very shortly after I was born and I performed a few of the sacraments as a child. By about 8 years old, I realized that the stories didn't make any sense. I still went to religion classes at my parents behest, though. I remember asking all kinds of questions to the Sisters who taught our classes. For example, I asked, how could a loving god damn people to the pits of hell for all eternity for not believing in him? Why did it have to be a "him" at all? What about all of the other gods that people believed in? And what exactly happened with the Ark? The dinosaurs lived way before humans, so how was that even possible?
By the time I was 12, I had had enough of religious classes and told my parents that I refused to go anymore. I told my mother that I didn't believe in God and she cried and then I turned around and pretended for a while longer so I could be a Boy Scout and not make the people in my family upset. I even had a short stint as an Altar Boy! It was around the time of Confirmation that I quietly told my parents that I was no longer going to church and that I really didn't believe in God.
They urged me to learn more about religions and try something else, because they felt that a good person needed to have that spiritual core in order to be moral in this world. I followed their advice and learned as much as I could about different religions. I became fascinated with Eastern Religions in High School because of my martial arts training and read a lot about Buddhism and Taoism. When I got to college, I was exposed to philosophy and ethics and that pretty much ended my participation in any religion. Based on a few philosophical principles, I knew that there not only was no such thing as a God, but that such a being could never exist. Gods are self contradictory propositions that explode upon rational contact like balloons and needles.
This is when I first used the term atheist to describe myself.
Moving forward, it's been very interesting raising my own children and teaching them about religion. My children love learning about mythology and religions, but we treat all of them to the same rational analysis that we apply to other areas in our lives. We ask questions like, what exists? How do you know? Do things exist if you don't know about them? Does anybody know something if there is no evidence? I don't come right out say that there are no gods, but I do treat them as stories. My son and I like to joke about converting to Odinism and we talk about what that religion must have been like. We are friends with lots of religious people and I think the lesson we try to get across to them is that people believe in all kinds of different things. Most of it, if not all, might not make any sense to you, but it's still important to them and it's important that you don't devalue them as a human being for believing in one of those things.
In my ideal world, I would like to see religion fall away from humanity as a relic of our irrational and violent past, but I don't see that happening in my lifetime or even my children's lifetimes. So, instead I practice religious tolerance, sufferance, and camouflage. Tolerate the religions that are harmless. Suffer those that are annoying. Hide from the dangerous ones.