Nate Paxton uses a neologism that I immediately find very appealing: Christianists. The obvious parallel is to the "Islamists" that hawks love to talk about. I plan to refer to fundamentalist Christians as Christianists from now on and hope that others will too. Andrew Sullivan calls them "theocons," but I hope he starts using "Christianists," as they are both illiberal in the same way.
(Before anyone says that Christianists don't explode suicide bombs and so on, I was making the comparison to Islamists not in terms of acts of political violence, but in terms of worldview and ideology. Moreover, apocalyptic violence is part of the most radical of "Islamism," but not essential to it.)