As for the depiction of Christians, I think when you see ones like the purifiers and Stryker, it's an attempt to show the real life, ultra hardcore Christian groups. The kind that go around with the "God hates fags" signs promoting hate for various sections of society. I don't think any good comic writer would depict all Christians in that way.
I think most people forget that (superhero) comic books are
filled with metaphors, some subtle most not. If a character or group is made to look stereotyped, it's probably because the writer is trying to fit a lot of information into a small space to get his/her point across to a vast readership, many of which won't grasp subtler undertones and will therefore miss the message.