Pretty broad and pretty simple.
Why do religions have more of a problem with atheism than other religions?
I call myself an atheist but some people have said I am more agnostic. To clear up I don't believe in god as depicted in the bible. I do not believe any omnipotent being had anything to do with the bible or any other holy book.
I do however accept that there are things we do not understand and may never understand.
What I don't get is why religious types see atheists as more of a threat than other religions.
Before I say anything, I have to warn I didn't read the thread at all, so anything I say that has already been mentioned, forgive me.
Now, onwards to the question.
Threat perception is more often than not a bilateral affair in that both parties peceive some sort of threat from each other for friction to be perpetuated. It takes two to tango in all cases, and such continuous wars on religion and God and who is right in their beliefs implies that both parties feel threatened enough to develop animosity.
If someone to whom you address a religion-related question bristles or immediately becomes defensive, chances are that:
1. you asked something they too secretly are asking and are afraid to look for the answer to, thus becoming angry when you force them to address the issue that frightens them as well even at a superficial level
2. they don't know the answer to your question and feel that it's a blow to their belief that they do not
3. they are manipulators that don't much care about the religion (or atheism) they are profession to adhere to but DO care to subdue their peers with their assertions, thus when questioned their authority is threatened and they try to bite your head off
4. they have been so traumatized by being ganged-up upon solely on the basis of their beliefs that they don't stop to check whether you and your questions are sincere or just an excuse for them to become targets and punching bags, so they blow up at you in advance just to save themselves the harassment.
I think you can see that this can hold for both atheists and any religion followers, be they Christian or Pagan or Muslim or what have you.
There has been much bad blood from both sides, due to evil people that have used ideals and beliefs and faith for their own nefarious purposes, cheating people into following them rather than follow the Creed they officially ascribe to, that it takes a lot of personal introspection, thought and respect of Human Rights to be able to rise above this exact mutual threatening feeling when the subject of religion vs atheism is breached.
It also takes a lot of faith not to pounce on someone who doesn't share your belief and dogma- and in my experience, it also means not to be ingrained to typolatry and the official churches, who pretty much fanatize people even in the cases where that is in breach with the actual Dogma.
My two cents for you, as a Christian and a Hellene :)