I'm not sure why it might surprise people that Hamas could use a church or its vicinity for their activities?
I mean, it's not like they have any love for chrisitans ("after saturday comes sunday "is one of their sayings)
For them, it's a win win situation. If Israel attacks a church, that's great for Hamas. And if it doesn't, that's great for Hamas.
Of course, I don't know for sure. But I do know a lot about Hamas and how they operate and what they are capable of. So it's not really much of a stretch of the imagination. Although I can imagine the Christian community is not really in a position to say to no to Hamas either.