While the prospect of a truly Faithful adaptation of Lewis's theology might flip the usual script and create an epic fantasy series that could actually appeal to and excite the Evangelical base instead of drawing their ire (Harry Potter etc.), it would be less likely to hit a homerun with the the broadest audience sought by such a tentpole endeavor. American viewers are increasingly secular and don't want their escapist sci-fi/fantasy fare to preach to them about Jesus.