My parents never taught me religion. The only time we went to church was for funerals, weddings and christenings. I went to a Church of England primary school, and while we did have Friday morning assemblies, we were not taught religion. At high school we had religious education classes, but in that class we learned about many religions, not just christianity. In other words, it was left to me to decide what I believed in but I didn't really give it much thought. That is, I was not force-fed any belief system and I did the same with my son. I left it up to him to decide. His mother was Buddhist but didn't push her beliefs on him either. Years later, in his twenties, he became very religious of his own volition, following catholicism, then a few other groups in Bangkok such as baptist, evangelical, etc. But ultimately he came to the conclusion that it was all a lie. How did he reach that conclusion? The priests, vicars, and whatever else they were, couldn't or wouldn't answer his questions on their faith and some even told him not to ask questions, but just to believe or leave. He also read the bible from cover to cover, and other reading materials, but finally said they did not make sense on a lot of issues (hence his questions which went unanswered).
So now, like me, he is an atheist and believes this is the only life we have.