Made it to the end of the demo. When it showed which girl you were most likely to go to the dance with, I ended up with no one lol. I guess I didn't focus on 1 girl enough, though it seems a bit too soon to be focusing on one when the characters have barely been introduced?
I felt the Christianity parts of the story were a bit disconnected with the monster girl parts. It was like switching between a Sunday School lesson and an anime dating sim lol. Perhaps the girls could mention Christianity more in casual conversation; just something small like saying "I'll pray for you" or something. The Christianity parts also seemed a bit too detailed, for example it might be better to just have Father John say a couple of sentences instead of a whole multiple paragraph sermon. Also perhaps you can tie in Christianity to the characters' personal stories - like one of the girls could be dealing with a family that doesn't accept her faith (though you might've already been planning something like this for later).
The MC did seem like a bit of a Mary Sue to me, since he's brave enough to fight bullies and disciplined enough to maintain a regular exercise schedule and do his morning devotions every day and popular with the ladies (although that last part is expected for the genre).
Overall though I think the game has potential and the setting is interesting. Good luck!
EDIT: I just had an idea. Have a scene where MC is about to have sex with one of the monster girls but then go "Whoops! Can't show this in a Christian VN!" Lulz.