I noticed a fair bit of the "I don't like people trying to convert me" vibe, so I thought I would post a bit on that. Note that I do not condone such action, nor do I claim that all people who perform such actions think like this, but rather that some do.
My cousin does not like to eat his vegetables. During meal times, there will usually be a point at which he has eaten the rest of his meal, leaving the vegetables till last, and then try to refuse to eat them. As far as he's concerned, there is no reason for him to eat his vegetables - they taste nasty and he doesn't like them. He's quite convinced that he's mature and responsible enough to decide what he wants to eat, and insists this regularly. He even argues that his parents are robbing him of the right to choose the very food that sustains him - and surely there can be no greater crime than this.
To a lot of the religous people, other people (be they atheist or of another religion) are like children that won't eat their vegetables (follow the right religion). Sure, they may make a lot of arguments about how they're mature and responsible to choose what they eat (what religion they follow), and they even argue that it's their right to make such decision regardless of other people's influence. But it is the religous people who know best (know the right religion), and they can't just stand around and do nothing while these poor misguided people have an unhealthy diet (go to hell).