Possible horror movie.
A man with a beard (and maybe glasses), walks alone at night suffering from hallucinations and remembering things from his past too.
We see a flashback of him as a child, where he and his friend burned their teacher and we watch clearly the teacher burn to death.
Another flashback shows him in a house, where a woman with short hair (probably his wife) is sitting at the kitchen table and is complaining at him about something. He says nothing and then suddenly strangles her to death.
After these flashbacks, he enters a church and sits next to another man, trying to hear the preaching. But he's not feeling ok due to his hallucinations and the man next to him asks him if he's alright.
Then he turns to see the man that spoke and instead of him there is another hallucination again, a horrible green monster that tries to attack him and he leaves the church terrified.