Why would you do that??
I understand that religion is the one which currently has a large number of folks which are radical, but why would you do something so insane?
Wouldn’t it be more effective to target oh.. maybe countries specifically which are supporting Isis/the enemy?
If you blocked all Syrian's as an example, you would be blocking Christian Syrians as well. We all know the Christians are true refugees in this area.
How do you exclude non-Christian Syrians?