The eighteen-year-old C.S. Lewis was hardly what one would call an athletic young man. He was a failure at sports and spent his school days avoiding the company of upper-class athletes. And yet, in 1917, the bookish Lewis chose to enlist in the First World War. I say chose because Lewis, as an Irish citizen (he grew up in Belfast), was not subjected to the draft. Nevertheless, he served and fought in the trenches, returning to England a year later as a wounded veteran.
Though he was too old to fight in WWII, he supported the war effort in every way he could, including speaking over the BBC radio and giving live talks to the RAF. In 1940, he even addressed a pacifist society in Oxford on the reasons why he (Lewis) was not a pacifist (his speech is anthologized in The Weight of Glory and Other Addresses).
In his talk, Lewis respectfully reminds his audience that when Christ instructed his followers to turn the other cheek, he likely meant the command to refer to personal situations between people and their neighbors. There is no indication that the command was meant to apply to all situations at all times. Surely, Lewis argues, “turn the other cheek” does not forbid me from coming to the rescue of someone who is being chased down by a maniac with a knife!
Christ calls upon us not to harbor a spirit of self-righteous hatred and retaliation toward those who have injured us. But that does not mean that magistrates, parents, teachers, and soldiers should suffer themselves to be struck by citizens, children, students, or enemy combatants.
Besides, Christ himself showered his greatest praise upon a Roman military officer (Luke 7:9). Likewise, when John the Baptist was approached by soldiers in search of spiritual advice, he did not tell them to quit their jobs—he merely told them not to extort money or accuse people falsely (Luke 3:14). Both Peter (1 Peter 2:14) and Paul (Romans 13:4) called upon the early church to obey magistrates, who do not bear the sword in vain.
In Mere Christianity (III.7), Lewis makes some of the same arguments, though this time he calls on his readers to examine their own hearts carefully. All killing, Lewis insists, is not murder: a proper translation of the Ten Commandments would read “Thou shalt not murder,” not “Thou shalt not kill.” Still, if we ourselves hear about the death of enemy soldiers or the execution of a criminal and rejoice in the loss of life, then we have fallen outside the high call of Christ.
“We may kill if necessary,” writes Lewis, “but we must not hate and enjoy hating. We may punish if necessary, but we must not enjoy it. In other words, something inside us, the feeling of resentment, the feeling that wants to get one’s own back, must be simply killed.”
Yes, Lewis knew and felt that war was a dreadful thing. No one who fought in the killing fields of WWI could doubt that. Still, Lewis believed that if we could remove the hatred and resentment from our soul, if we could free ourselves from brooding on revenge, that war could be approached courageously with “a kind of gaiety and wholeheartedness.”