So is John a Believer now or what ?

Not sure if the Exorcism was a set up or not but looked real ?! If so is John now a Believer or has he let the Demons come back sevenfold ?? (If you believe that kind of thing) Did he end up Evangalising with the American dude ??
Hard to find answers anywhere.

"What we've got here is... failure to communicate. Some men you just can't reach."