Sabra and Shatila refugee camp massacres where a Lebanese Christian militia during the Lebanese civil war killed upwards of 3,500 Palestinian and Lebanese Shiite civilians under the watch of the IDF.
The unfortunate reality of civil wars is that there are no innocent parties. There are Christians fighting in the Syrian civil war. Moreover the United States requires no religious test for entry, to do so would be against the very defining core of this country. As long as they are fleeing a civil war because their homes have been destroyed, we should help them regardless of their religion. To alienate Muslims and only allow Christians is to only further Daesh's goals and rhetoric where they say that the final conflict between Muslims and non-believers is approaching. We cannot let Daesh win the ideology war, we cannot help them.
I'm unsure as to why you want to help Daesh.