I'm generally atheist and I find Christianity very interesting. Christians, for the most part, aren't. If atheists don't find it interesting that is probably because it has little relevence to their daily life, and I don't blame them. For atheists, the Christian God, the greek Gods, and the Gods of the Aztecs are the same sorts of inventions. Religion doesn't have the variety of roles in society that it used to. The study of comparative religion is especially fascinating, as we can see an "evolution" of religious thought corresponding to other changes in human culture, like the rise of civilization and agriculture.
Religion is a kind of mental technology, providing a shared ideology that unifies the population, defines their role in society and the universe, and gives comfort to a rapidly evolving primate now capable of self-reflection. Wether it is true or not is kinda beside the point. Religions have offered up a variety of bizzare ideas to humanity, and Christianity is no exception (original sin, Satan,etc...). It is interesting that Jesus didn't design Christianity himself, and would probably disagree with many of it's forms, and also that it has adapted over the years to scientific truths, like the earth revolving around the sun. It's also interesting that the concept of Jesus sacrificing himself for humanity emerged from a long tradition of sacrifice, which probably orginated from human sacrifices, then evolved to just animals (more practical, and who doesn't like a good barbeque), then to single acts of sacrifice like Abraham and Isaac (which didn't have to actually happen to be significant), then the sacrifice to end all sacrifices of Jesus (whew, finally we're done with that).