“So…what was really going on? Was God informing the dead priest? Or was the priest’s spirit working on knowledge he gained from these people in confession about the bad things they were planning to do or wanted to do? Trying to stop them before the did it. It would all have been okay if it didn’t turn other “regular” people into murderers. It sounded like the spirit of Father Gregory promised them redemption for carrying out his requests to kill bad people. Was that a real promise? Or was he promising something he couldn’t deliver?”
I don’t think God was involved at all. I think Father Reynolds prayed for deliverance from the violence going on in the neighborhood. Father Gregory (who can apparently read minds — a gift I don’t think I’ve seen in any other spirit in this show) thought he was answering Father Reynolds’ prayer when he decided that he was an avenging angel and started coercing people into committing murder. I think you’re right that Father Gregory got his information from confessions.
What’s always made me curious is why Father Gregory chose certain people to commit the murders. The two people we saw — the first woman and the drunk guy — were pretty messed up in life. Maybe they were in despair and/or vulnerable to manipulation, so that’s why Gregory chose them? If so, why did he choose Sam?