Apart from Aslan's resurrection in one book, which is quite heavy-handed, Christian elements don't seem to be that prevalent across the seven books.
Yet many people seem to be deeply suspicious that the Chronicles of Narnia are a form of propaganda which will indoctrinate their kids.
I know that CS Lewis was a part-time Christian evangelist (and full-time Professor of Medieval Lit), but the books themselves don't seem suffused with the doctrines in the way one might expect; and certainly not in the way they're sometimes described.