After reading Lewis's The Problem of Pain James Welch, the Director of Religious Broadcasting for the BBC, wrote Lewis the following:[1]
I write to ask whether you would be willing to help us in our work of religious broadcasting ... The microphone is a limiting, and rather irritating, instrument, but the quality of thinking and depth of conviction which I find in your book ought sure to be shared with a great many other people.[1]
Welch suggested two potential subjects. Lewis responded with thanks and observed that modern literature, the first, did not suit him, choosing instead the Christian faith as Lewis understood it.[1]
In the preface to later editions, Lewis described his desire to avoid contested theological doctrine by focusing on core beliefs of the Christian Faith.[2] The succinct and pithy language employed by Lewis enabled him to impact broad audiences, while retaining intellectual substance for more studied readers.
Every Wednesday from 7:45 pm to 8 pm during August 1941, Lewis gave live talks entitled "Right or Wrong: A Clue to the Meaning of the Universe" which would become the first book in Mere Christianity. The first set of talks became very popular and flooded Lewis with responses from an adoring and irate public. This feedback led to Lewis going back on air to answer listeners' questions.
The following January and February, Lewis gave the next set of talks on what would become "What Christians Believe". The talks remained popular and because of the success of the newly released The Screwtape Letters, Lewis’s publisher was happy to publish the broadcast talks as books that year.
In Autumn 1942, the third series of talks were, ironically, cut down from 15 to 10 minutes. Due to a miscommunication, Lewis had prepared for 15 minutes, but added the cut material back into the next book and added several more chapters.
The fourth set of talks did not take place until 1944. The script drafts had a much wider scope originally, and Lewis prepared for 10-minute talks when the BBC was giving him 15. The timing of these talks was important and strictly adhered to due to technology and World War II, Germany would broadcast propaganda through the English-spoken "Lord Hawhaw" during any dead air. Due to the timing of the fourth set of talks (10:20 pm), Lewis said he could not do them all live and would have to record some.
The Case for Christianity (Broadcast Talks in UK)
The core of the first section centres on an argument from morality, the basis of which is the "law of human nature", a "rule about right and wrong," which, Lewis maintained, is commonly available and known to all human beings. He cites, as an example, the case of Nazi Germany, writing:
"This law was called the Law of nature because people thought that everyone knew it by nature and did not need to be taught it. They did not mean, of course, that you might not find an odd individual here and there who did not know it, just as you find a few people who are colour-blind or have no ear for a tune. But taking the race as a whole, they thought that the human idea of decent behaviour was obvious to everyone. And I believe they were right. If they were not, then all the things we said about the war were nonsense. What was the sense in saying the enemy were in the wrong unless Right is a real thing which the Nazis at bottom knew as well as we did and ought to have practised? If they had had no notion of what we mean by right, then, though we might still have had to fight them, we could no more have blamed them for that than for the colour of their hair.[3]
On a mundane level, it is generally accepted that stealing is a violation of this moral law. Lewis argues that the moral law is like scientific laws (e.g. gravity) or mathematics in that it was not contrived by humans. However, it is unlike scientific laws in that it can be broken or ignored, and it is known intuitively, rather than through experimentation. After introducing the moral law, Lewis argues that thirst reflects the fact that people naturally need water, and there is no other substance which satisfies that need. Lewis points out that earthly experience does not satisfy the human craving for "joy" and that only God could fit the bill; humans cannot know to yearn for something if it does not exist.[4]
After providing reasons for his conversion to theism, Lewis explicates various conceptions of God. Pantheism, he argues, is incoherent, and atheism too simple. Eventually, he arrives at Jesus Christ, and invokes a well-known argument now known as Lewis's trilemma. Lewis, arguing that Jesus was claiming to be God, uses logic to advance three possibilities: either he really was God, was deliberately lying, or was not God but thought himself to be (which would make him delusional and likely insane). The book goes on to say that the latter two possibilities are not consistent with Jesus' character and it was most likely that he was being truthful.[4]
Christian Behaviour
The next third of the book explores the ethics resulting from Christian belief. He cites the four cardinal virtues: prudence, justice, temperance, and fortitude. After touching on these, he goes into the three theological virtues: hope, faith, and charity. Lewis also explains morality as being composed of three layers: relationships between man and man, the motivations and attitudes of the man himself, and contrasting worldviews.
Lewis also covers such topics as social relations and forgiveness, sexual ethics and the tenets of Christian marriage, and the relationship between morality and psychoanalysis. He also writes about the great sin: pride, which he argues to be the root cause of all evil and rebellion.
His most important point is that Christianity mandates that one "love your neighbour as yourself." He points out that all persons unconditionally love themselves. Even if one does not like oneself, one would still love oneself. Christians, he writes, must also apply this attitude to others, even if they do not like them. Lewis calls this one of the great secrets: when one acts as if he loves others, he will presently come to love them.
