[skissane]

It is totally possible to ask (or even answer) a question about a religion without believing in it.

"What are the differences between Shi'a and Sunni belief?" is a totally valid question even if you are an atheist or a Hindu. The answer to "What does the Catholic Church teach about abortion?" is totally independent of your own personal views on the topic.

One doesn't have to be a believer in a religion to be able to answer factual questions about it. Sometimes, an atheist, or a follower of a competing religion, may actually know more about a religion's teachings and history than many of the people who actually believe in it do, and so may actually be able to give more accurate answers about it than some of its own members can.