I think the first time I told them that I didn't believe in god,I didn't really know what I was saying.I was in 4th grade at a Catholic school and my mom was talking about going to church for Eadter and I told her "I don't see why I have to go to church,I don't believe in God.".She looked at me and gasped and was hostile then she told my dad and he lectured me on why I should believe in god.And I didn't think much about it for the rest of that time.But when I started listening to heavy metal,I started thinking darker and looking at all of the religion around me.And I realized that absoultely none of it made sense and I refused to believe in it.I kept my thoughts quiet until the issue of religion came up w/my parents.They saw that I was really into Marilyn Manson,and that terrified my mom.Sometimes I'll bring the issus of god up with my mom and she will be really terrible about it.She'll yell at me and say that music has "brainwashed"me and that I probobly worship Satan.She obviously thinks that if there is no god then there is nothing but Satan.So I try to avoid stuff like that around her as much as possible.My dad can be more understanding.He tells me not to be so sure that there isn't a higher power because I'm only 14 and I haven't been thru a lot.But religion is still a weak area to be on w/my parents.If your mom listens to Ozzy and Metallica then at least she won't say that you've been brainwashed by the music you listen to.As for telling them,try not to offend them and say that just because you don't believe in god that doesn't mean that you're a Satan worshipper.That may help them understand you more easily.