The Screwtape Letters, written by C. S. Lewis, is a fictional novel containing one hundred eighty-five pages. Published during the Second World War, it was featured in the Guardian newspaper.

Set in WWII-era England, The Screwtape Letters is an ingenious collection of fictional correspondences between Screwtape and his nephew Wormwood (both of which are demons). Screwtape writes his letters to Wormwood advising him on how to best gain control of his “patient.” Continuing throughout this monologue, Lewis points out many of the weaknesses of Christians and how the devil can use them to his advantage.

C. S. Lewis touches on many thought-provoking points, one of which is “the law of undulation.” This “law” is based on the fact that humans are both physical and spiritual beings who are always changing their minds. Constantly distracting humans, their regard for their physical being takes away their focus from matters concerning eternity. This creates a series of peaks and troughs in a Christian’s spiritual life. When a person focuses on these peaks and troughs, belief in God becomes an endless search for emotionally satisfying experiences which are of little use on their own. From another standpoint, if a Christian finds themselves in a trough and does not seek out more mature believers, they will be lulled into a place of moderated complacency. Moderated religion is the same as no religion.

The constant struggle in The Screwtape Letters is for the submission of the patient to the will and appetite of the devil. But, throughout the letters, there is an undying theme that eventually foils all of Screwtape’s advice to Wormwood-- the love of God for His people. This concept and the reason behind it could never be fully grasped by the demons, and therefore they could not find a successful way to counter it.

The Screwtape Letters is a masterpiece written by one of the most renown Christian apologists of the twentieth century. Artistically written, the narrative is so vivid one can almost hear the snarls of Screwtape as he scoffs at and scolds Wormwood. C. S. Lewis cleverly presents the weaknesses and shortcomings of human nature in such a thought out and logical form it is nearly impossible to deny its validity.