I have no evidence either way. Someone can believe in God and not be a Christian.
I would doubt that she was a Christian...she’s from a liberal family, so she was probably a deist. I don’t think she was a Muslim, but she was definitely a fool. Like many women, she was completely addicted to a man (her Syrian boyfriend, who was captured but released) and probably would have done anything for him.
Poor fool, poor thing. I only hope she died in the airstrike and not in some worse way.
“Someone can believe in God and not be a Christian.” Then they do not believe in God. They may have a fanciful understanding of a god, but apart from Jesus, there is no union or belief in God.