Preaching at the University Church of St. Mary the Virgin in Oxford on October 22, 1939, Lewis observed that
to a Christian the true tragedy of Nero must be not that he fiddled while the city was on fire but that he fiddled on the brink of hell. You must forgive me for that crude monosyllable. I know that many wiser and better Christians than I in these days do not like to mention heaven and hell even in a pulpit. I know, too, that nearly all the references to this subject in the New Testament come from a single source. But then that source is our Lord Himself. People will tell you it is St. Paul, but that is untrue. These overwhelming doctrines are dominical. They are not really removable from the teaching of Christ or of His Church. If we do not believe them, our presence in this church is great tomfoolery. If we do, we must sometime overcome our spiritual prudery and mention them.
Later he describes all those present as “creatures who are every moment advancing either to heaven or hell,” challenging them all, even in the context of the war, “to retain” an interest “in learning under the shadow of these eternal issues.”
–CS Lewis “Learning In War-Time,” in Walter Hooper, ed., The Weight Of Glory And Other Addresses (New York: Macmillan, revised ed., 1980), pp. 20-21