In this case, the religion of the refugees is inextricably intertwined with their politics, and their views toward America.
Even making a plausible argument that that's the case, I still fail to see how you can ensure an accurate litmus test for religious beliefs, and how applying such a test to filter potentially problematic people is anything but a bad idea. It would set a truly warped precedent. I would much rather see us trying to address the problem at the source, by enabling safe zones within Syria in an attempt to stem the tide of people fleeing the country.