Also, it's not like Muslims "don't believe in Jesus". They do, in fact, he's considered the second most important prophet in Islam. They do not accept his godhood, but he's as close to God as he could be (Islam is really big on the "monotheist" part, and the Holy Trinity is too big of a departure from that). Jesus is an extremely important person in Islam, and a Muslim writing about him isn't any different than a Christian doing the same. Knowing this, it's really funny to see this "Jesus vs. Muhammad" concept some extremists like to use. In fact, when you look at it, Christianity and Islam are really similar, much more than a lot of people would like to admit. Considering where they came from (starting out as Judaism adapted for Roman and Arab cultures, respectively), it shouldn't be surprising.