[AnAmericanMother]

Screwtape's rage at the "patient"'s ultimate salvation:

"The degradation of it! – that this thing of earth and slime could stand upright and converse with spirits before whom you, a spirit, could only cower…He saw not only Them; he saw Him. This animal, this thing begotten in a bed, could look on Him!"

[zot]

Yes, there are many insights in “The Screwtape Letters.”