The protagonist is a sociopath who trapped a bunch of innocent ghosts in a Stable Time Loop so he could kill them over and over again.
Perhaps he feels they wronged him somehow, or perhaps they were in the wrong place at the wrong time. Regardless, they are permanently trapped in an endless loop where they are killed by a madman with a chainsaw. The text is actually a voice in his head.The door sending the protagonist back in time is part of a Xanatos Gambit by the ghosts to keep him from stopping a much grander scheme.
The entire game, in fact, was a diversion, allowing them to go unchallenged when they try to summon some Eldritch Abomination in order to destroy the world.The protagonist is insane
The entire game is his delusion, with the ghosts representing some repressed issues, and the door being a sort of false escape he somehow falls for every time. The fact that going the other way or avoiding the door traps him in an endless void forever is part of a "you can't escape/run away from your problems" thing. Alternatively, it is a recurring nightmare
And every time he goes through the door, he wakes up, only to dream it again the following night.