I don't have much time right now, but what is everyone's problem with religion?
Everyone's? I don't have any real "problem" with religion. I think that religion is probably inevitable in human beings and I find it fascinating. I feel a sense of religiosity myself, to tell the truth, and I actually kind of like religion. It's my academic area of study.
Of course there are varieties of religion and religious behavior that I don't like. I'm not very friendly towards hard-core militant Islam for example. I have little fondness for Christian fundamentalism either. I'm totally unmoved (or perhaps moved in a hostile direction) when fanatics wave Bibles or Qurans at me.
I take it that you're asking why some of the militant atheists display such bitter and implacable hatred for religion. (Usually for Christianity specifically.) I've wondered that too.
In some cases, it might be because they are former Christians who have subsequently lost their faith. So they feel anger and bitterness at the faith that they feel has failed them. In other cases, they are people who were raised in extremely religious homes who experienced quite a bit of psychological pressure and hostility when their disbelief became known. Kids have occasionally even been been shunned by their families and thrown out onto the street. (That happens with gay kids too.)
One thing that's always struck me is how intellectually similar Christian fundamentalists and militant atheists can sometimes be. There's the same intolerance towards dissenting belief. There's the same sense of evangelical mission. There's the same eschatological belief in a coming day when their beliefs sweep all else aside. And there are even close simularities in how they relate to scripture, in their literalistic interpretations, their reliance on proof-texts, their insistence that Christians accept Biblical inerrancy, their condemnation of 'picking and choosing' which Bible verses to believe in, and so on.
(You haven't lived until you've been lectured by a discussion board full of atheists on what "true Christianity" is and must be.)
I can only guess that it's the result of upbringng, that many of the angry atheists come from - and are reacting against - strongly Christian homes.