I've read a few of the initial posts here but have skimmed/skipped the rest because so much of it has become a BNP discussion and, as an American, I feel that the BNP itself is irrelevant to me (though I am glad to be made aware of folks' concerns with it, in a beware-the-wolf-at-the-door sort of way).
As far as the discussion of Mudcatter meanness toward Christians is concerned, I'm not sure that one can generalize it quite like that. Certainly there is meanness by right-wingers toward left-wingers and vice versa, and in America, at least, that often means meanness by the religious right toward those they consider "secular" and vice versa. But if conservative-bashing and liberal-bashing have turned into religion-bashing, I must have missed those threads.
I will say that, as an atheist who does not believe in any sort of life after death (including sentient-but-bodyless spirits of any kind), I have sometimes been treated in a mean-spirited way at Mudcat by those who take offense at my attitude toward the dead.
For instance, when Ted Kennedy passed away and an "Obit" thread was started, I was not the first poster to mention Chappaquiddick but I did make a metaphorical statement that, because that incident will forever be associated with Kennedy in the history books, he will "never rest in complete peace". Oh, what a hue and cry resulted from that! The worst responses: Kat was calling me "rude, ill-mannered and judgemental", demanding to know "You sit at the right hand of whatever god you think might declare that? Such arrogance..." and apparently wishing bad "karma" upon me. Meanwhile, Spaw seemed to think that I was declaring myself as having "been so blessed as to be given the gift of perfection" and, since in his opinion I had "cast the first stone" at Kennedy for being imperfect, Spaw threatened to give me a hot lead enema ("just bend over while I get the funnel").
So I submit to you that it's not just Christians who are the recipients of "nastiness" by those of a different religious belief here at Mudcat.