Why do a lot of Athiest not like Christians and try to convert people.?

PLEASE READ: I mean, why bother trying to tell me there is no God? I believe in God, let it be. Why do most of them (MOST NOT ALL) just try so hard to convert? It just makes me sad when people try to do this, because I believe and it's mean and hypocritical to try to force me into Atheism. I'm not trolling, just answer the questions and no diehard Christian/Atheist/Whatever rants. And, Most of us aren't stereotypical Jesus Freaks. I listen to Hard Rock, Metal, Masturbate and stuff, but I still believe in God. He forgives me for that stuff. NO RANTS.