The Exorcist ending explained

What happens

The ritual kills Merrin, and Karras goads the demon into himself, then throws himself from the window to the steps below. The demon dies with him. Regan, freed and remembering nothing, leaves Washington with her mother.

The last image

Regan and Chris drive away from the house, leaving behind the steps where Karras died.

What it says

Karras, who had stopped believing, proves his faith only by giving up his life, and the film suggests sacrifice can answer guilt. Evil is beaten at a cost, not for good, which is why the ending feels quiet and unsettled.