Pew research does per-country religious belief surveys. I think you will find it very enlightening to look up the religious beliefs of the average Syrian.
And can you tell me what makes someone a refugee? Whether an average refugee is ideologically/culturally identical to the average non-refugee from that country? And how about a refugee who's choosing to go live in a country very different from their own?
Pointing us to "per-country religious belief surveys" is incredibly simplistic.