I sense the films events happened after he died, not in the process
I think he spent time in purgatory after death but went to heaven. It was discided he was ultimately a good person and the demons did not get him, though they really did try.
I don't believe the films events happened when he was in the process of fighting for his life but after he died. Though in our time on earth his battle after being declared dead was fought quickly. That's why he looked peaceful after death because a few minutes on earth were about 5-7 years in the purgatory realm for him. The observers of his dead body in our realm saw his expression of being at peace likely within minutes though.