Yes, Sonlight is a Christian Curriculum, but mostly it is just great books. Some Christian's won't use it because it uses some books that are not from a Christian background. On the other hand some of the books that they use are very Christian and you would want to leave them out if you are not.

The thing I like about it most is that you read these really thought provoking books to your kids and then you talk about them. Your kids get to learn from YOU. They learn to think about books and not just accept whatever they read. At first I wondered about how it would work, but I really feel that my girls have learned a lot, even from characters/authors that have very different beliefs than we do.