The strange and typical fact that in this article about the shooter, no word about his religion. Stoneman Douglas High School was a public school, but if he had been non-religious or Muslim, the article would most likely mentioned that. The fact that no word is spend on the religious background of Nicolas Cruz, makes me assume that he probably lived in a Christian community. At least, more or less, because he was adopted, and after his adoptive parents died, transported to family.
I wonder if this more or less educated guess of mine proves to be right. Because, of course, I don't know.