In The Screwtape Letters, C. S. Lewis masterfully “teaches in reverse” by wryly using demonic points of view to enforce a biblical one. He calls it “diabolical ventriloquism.” Here is a one-sentence summary of each of Screwtape’s thirty-one letters that advise Wormwood how to tempt his “patient” (who becomes a Christian between letters one and two):

1. Make him preoccupied with ordinary, “real” life—not arguments or science.
2. Make him disillusioned with the church by highlighting people he self-righteously thinks are strange or hypocritical.
3. Annoy him with “daily pinpricks” from his mother.
4. Keep him from seriously intending to pray at all, and if that fails, subtly misdirect his focus to himself or an object rather than a Person
5. Don’t hope for too much from a war [in this case, World War II] because the Enemy often lets our patients suffer to fortify them and tantalize us.
6. Capitalize on his uncertainty, divert his attention from the Enemy to himself, and redirect his malice to his everyday neighbors and his benevolence to people he does not know.
7. Keep him ignorant of your existence, and make him either an extreme patriot or an extreme pacifist who regards his cause as the most important part of Christianity.
8. Make good use of your patient’s series of troughs and peaks (i.e., “the law of undulation”), and beware that the Enemy relies on the troughs more than the peaks.
9. Capitalize on trough periods by tempting him with sensual pleasures (especially sex), making him content with his moderated religion, and directly attacking his faith as merely a “phase.”
10. Convince him to blend in with his new worldly acquaintances.
11. Understand the four causes of laughter (joy, fun, the joke proper, and flippancy), and shrewdly use jokes and flippancy.
12. Don’t underestimate the power of “very small sins” because “the safest road to Hell is the gradual one.”
13. Don’t allow him to experience real pleasures because they are a touchstone of reality.
14. Make him proud of his humility; use both vainglory and false modesty to keep him from humility’s true end.
15. Make him live in the future rather than the present.
16. Encourage church-hopping.
17. Encourage gluttony through delicacy rather than excess.
18. Convince him that the only respectable ground for marriage is “being in love.”
19. Understand that the Enemy does not genuinely love humans (but we don’t know what his real motive is).
20. Don’t give up if your direct attacks on his chastity fail; try to arrange a desirable marriage.
21. Convince him to use the pronoun “my” in the fully possessive sense of ownership (e.g., “my time,” “my boots,” “my wife,” and “my God”).
22. Understand that the Enemy has filled his world full of pleasures and that you must twist them before you can use them.
23. Encourage him to embrace a “historical Jesus” and to treat Christianity as merely a means to a political end such as social justice.
24. Confuse him with spiritual pride for being part of an elite set.
25. Replace “mere Christianity” with “Christianity And” by increasing his horror of “the same old thing” and thus increasing his desire for novelty.
26. Sow seeds of “unselfishness” during his courtship.
27. Twist his prayers.
28. Guard his life so that he grows old because real worldliness takes time.
29. Defeat his courage, and make him a coward.
30. Capitalize on his fatigue, and manipulate his emotions with the word “real.”
31. His end is inexplicable, but we must win in the end.

–From my review of C. S. Lewis, The Screwtape Letters: First Ever Full-cast Dramatization of the Diabolical Classic (produced by Focus on the Family Radio Theatre). Themelios 34 (2009): 454–55.

P.S. This is one reason that Professor of Defense Against the Dark Arts is actually not a bad title. “Our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms.” See Eph 6:10–20.