Screwtape praises Wormwood for his excellent progress in corrupting the patient, but warns him that if he moves the patient away from God too quickly, the patient will become aware of what is happening and try to regain his Christian faith. Ideally, the patient should continue to think that he is a pious Christian.
Another major disadvantage of the devils in their war with God is that can’t succeed “too much.” In other words, if they pull humans into evil too quickly, they will fail to keep them in a state of sin. When one thinks about famous tragic plays and novels, the hero’s slide into evil is always slow and gradual, just as Lewis describes.
Wormwood should try to inspire a feeling of vague dissatisfaction in the patient. This feeling shouldn’t be powerful enough to “shock” him back into piety, but a weak sense of dissatisfaction will make the patient reluctant to think about God any further, or even to go to church. Over time, the patient will become unhappy and dull, and he’ll spend long chunks of time talking about boring subjects, staring at the fire, etc.
It’s a longstanding tenet of Christianity that to be evil is to be miserable. There’s no way for a sinner to be truly happy—only to experience some pleasure in the short term. Lewis explores this idea, suggesting that the development of a vague displeasure is another obstacle to piety and joy.
Screwtape notes that Christians think of God as a being “without whom Nothing is strong.” In a sense, Nothing is the devils’ greatest weapon—Nothing will encourage the patient to avoid God and feel miserable. Screwtape encourages Wormwood to push the patient away from God, one small sin at a time—“the safest road to Hell,” he says, is gradual.
One of the more interesting implications of this section of the book is that evil isn’t, properly speaking, a “thing.” Evil is the absence of Good or piety—a vacuum which humans don’t know how to fill.