I wouldn't say Christianity is the only religion that's interested in the historicity of its major claims. The monotheistic religions are generally more invested in the alleged details of their historic origins than are the Eastern religions. But Islam, for instance, doesn't need to rely as much on the dubious historic claims about its founding prophet's miracles because Muhammad had a much bigger direct impact on history than Jesus. And most Jews are secular humanists who outgrew the childish, exoteric literalism.

I'd say, then, that Christianity is indeed a special case. However, I'm also especially interested in that religion.