In S011E08, the Doctor says, offhandedly, that she's "not a great believer in Satan."
However, in "The Impossible Planet" and "The Satan Pit," the Doctor met the Beast, which, while not precisely the same entity as the one from Abrahamic lore, has the general physical appearance, possesses people, and basically calls itself Satan.
She also must have heard about its son, Abbadon, from Captain Jack Harkness.
Why, then, does the Doctor say this?