Yes I was immersed in Christianity, at school, at Church, at home, all my daily activities, etc. And yes, I was very religious, praying all the time, going to mass daily, reading the Bible and saying the rosary every night, sometimes getting up at 5 am to pray and say the rosary before school...
Any way, I just got tired about feeling guilty all the time. Guilty about every time I had sex, guilty about every hard-on I got when I saw a hot girl, guilty for jerking off... I also disagree with the Church's (and most of Christianity's) stances on contraception, gays, and sex... There's alot more to it than that but I will spare you, these are the main ideas.