My remembrance of this episode is a little sketchy, given that it aired in 1972, but I remember being freaked out by it. The gist of the story: In Wales, there was a man designated as the village "sin eater". He would feast on food laid out on a corpse, and "absorb" all of the sins committed by the deceased during their lifetime. Richard Thomas' character is the son of a "sin eater" who has just died. His mother (the wonderfully borderline-nuts Geraldine Page) doesn't want her dead husband roasting in hell, with all the sins he's "eaten" over the years, so she cajoles the son into "eating" all the sins from the dead father.
He does it. And it's horrifying.