In this final book, Lewis speaks about the “so what” of the Christian life. Book III on Christian Behaviour goes far beyond the theological snobbery. In past times in Church History, theology was not seen as being application. This idea changed radically with William Ames (the Puritan), and more contemporary thinkers in the Reformed and Anglican tradition that stress theology is practical. After all, what would be the sense of theological inquiry if it had no application beyond the classroom or Star Bucks? Biblical theology is ethical and so are all things. If we deny that, we return to the abstractionism of the Greeks.
C.S. Lewis discusses then the three ideas of morality:
Morality, then, seems to be concerned with three things. Firstly, with fair play and harmony between individuals. Secondly, with what might be called tidying up or harmonizing the things inside each individual. Thirdly, with the general purpose of human life as a whole: what man was made for: what course the whole fleet ought to be on: what tune the conductor of the band wants it to play.
Allow me to summarize Lewis in three words: Human morality is concerned with a) relationships, b) internal, and c) eternal. In this last point, the reader needs to realize that morality goes far beyond our lives here. It prepares us for a life to come. In my own thinking I have tried to ameliorate that absurd notion that our goal is to forget this evil world and prepare for the next. This does not seem to be the idea of the apostle Paul nor of Jesus. Nevertheless, the world to come is of significance to all because our morality may be motivated by it. This should not be a meritorious motivation (Ephesians 2:8-10), but as a sign that there is more to life than this world. C.S. Lewis writes:
Christianity asserts that every individual human being is going to live forever, and this must be either true or false. Now there are a good many things which would not be worth bothering about if I were going to live only seventy years, but which I had better bother about very seriously if I am going to live forever.
This is brilliant logic! Why should anyone live decently if this is all there is to it? Sartre would be right. Nietzsche would be right. But existential atheism is immoral, because it denies the life to come. This is the already, but the not-yet is around the corner for any of us. Morality is crucial in this respect. As in Pascal’s wager, if you live immorally you have everything to lose, but if you live morally under the guidance of a sovereign authority, you have nothing to lose.
This world is not eternal. The hyper-Preterist (probably unheard of in Lewis’ day) is wrong in denying that this present world will end one day. Christ will make all things new through the purification of all things. He will not annihilate this world, but bring it to its intended use. It will be a sort of perfect, perfect Eden. Since the earth, in its present form is not eternal, then some elements of this earth are also not eternal, like the state.
If individuals live only seventy years, then a state, or a nation, or a civilization, which may last for a thousand years, is more important than an individual. But if Christianity is true, then the individual is not only more important but incomparably more important, for he is everlasting and the life of a state or a civilization with his, is only a moment.
The idea that the state is only a temporary tool in the hands of God to preserve justice is powerful indeed. In the New Heavens and New Earth, justice will have been completed and civil government as we know it will be done away with, since there will be no more role for justice, since all justice has been fulfilled in Christ’s second Advent. Nevertheless, in hell, the state will also not exist, though that righteous justice will be applied negatively forever. This is what Gary North would term, the eternal negative sanctions of the covenant.
This holistic theme in Lewis leads to the idea of the intellect. We have been speaking of Lewis’ idea of morality. But true morality is implicit is true theology. The thinking is not absent. In fact, God hates slack (Proverbs 10:4; 18:9). The slacker or lazy will have a hard time entering into a new kingdom where strength, courage, and honor are exalted. This has nothing to do with height or physical strength (consider Frodo). Lewis explains:
God is no fonder of intellectual slackers than of any other slackers. If you are thinking of becoming a Christian, I warn you you are embarking on something, which is going to take the whole of you, brains and all.
Christianity is not alluring at first sight. It is like Christian’s journey in Bunyan’s Pilgrim’s Progress. It is filled with difficulty and turmoil. Bumper stickers that speak of “Have Joy, Have Jesus” are speaking devilish non-sense. One must count the cost if he is to embrace the gospel. It may even require leaving family and friends. And your brain always comes with you in this new journey. As Lewis mentioned, it requires brain and all. The modern aversion to intellectual endeavor is sinful. In fact, the Christian faith calls for believing intellectuals who at one hand can read the mysteries of Revelation and on the other hand, read of the details of daily living in Proverbs. It is an unbroken unit.
Christian Behaviour touches on much more. Among them are the seven cardinal virtues. In order to briefly speak of one of these elements, let us hear the words of Lewis on the virtue of temperance:
Temperance referred not especially to drink, but to all pleasures; and it meant not abstaining, but going to the right length and no further.
The inception of fundamentalism urged that Christians in all places cease to drink their beer and wine. Why? Because they limited temperance to drinking alone. The Sunday morning minister who shuns alcohol and proceeds to indulge his flesh in a buffet is a sinful hypocrite.The teetotalism that Lewis speaks of is a misapplication of the law of plentifulness. God has given us wine and drink so that we may enjoy his bountifulness. Christians forget that their liberties are not tools for abuse, but tools for refreshment.
Some struggle with certain sins, like alcohol and as a result they deny the cup of wine passed to them at the Eucharist. They think it will tempt them to return to their bad habits. This is once again foolish and has led to the unbiblical notion of grape juice in the supper. This is a result of the early anti-alcohol amendments. Do you think that there were alcoholics in the first century? Of course. Do you think alcoholics back then struggled with temptations in this area? Of course. Then, why did Paul still serve real wine in the Sacrament? He did because no sin or temptation can overcome the shedding of blood of our Lord. The wine serves as perpetual reminder that our sins are blotted out and we are made new through this covenant communion.
Some will try to impose their temptations on others by saying that since they do not drink, then you should not drink either. To which Lewis responds,
One of the marks of a certain type of bad man is that he cannot give up a thing himself without wanting every one else to give it up.
Christian Behaviour is to be an impetus to all people enjoying all things.This is similar to Luther’s idea that the abuse of something is not an argument for its proper use. Because someone enjoys that which you are tempted with, is no reason to expect that they give it up for your sake (unless mutually agreed upon). When all things are used properly, then Christian Behavior is seen in its proper light—the light of Christ.
 There is a fourth book in this copy of Lewis’ Mere Christianity that deals with issues Trinitarian. They, as far as I know, were not originally part of the talks. Therefore, they will not be added to this discussion.
 Greg Bahnsen, John Frame, N.T. Wright and others all stress the ethics of the Bible.
 Mere Christianity, pg. 71.
 Ibid. 73.
 With the possible exception of the British author James Stuart Russell.
 Ibid. 73.
 Romans 13.
 Lewis, 75.
 Ibid. 76.
 At least on two grounds, gluttony and Sabbath breaking.
 Mere Christianity, pg. 76.
 Granted, I will not offer the alcoholic a drop of wine in my home. But the issue at the sacrament is an issue of command.