The man in the cathedral is not Red John.

The man Patrick chases in the park is Red John. They are NOT the same person. Also, he was in the cathedral at the end of the last episode. So that will be the beginning of the next episode. The man with the gruff voice is communicating on behalf of Red John. Patrick will pretend to give him mercy, because he KNOWS it's not Red John.

Then Red John, aka Brett Partridge agrees to meet him in the park. PJ chases and slays him. That's my guess.