I can’t figure the name of this horror movie

I need a lot of help on this one. I want to say I can remember tidbits, but that’s it.

I want to say the setting was several people locked in a scary church for some reason. In short, Satan was coming. Towards the end, he was specifically coming through a mirror. One of the people locked in may have been pregnant with Satan’s baby. Lastly, I want to say there was some “message from the future” being transmitted to one or more of the people in the church, but they could never figure out what it was.

HELP!!!!