Christians inhabit two kingdoms: the kingdom of God and the kingdom of this world. Jesus confirmed this when he said, “Render unto Caesar the things which are Caesar’s, and unto God the things that are God’s” (Matthew 22:21).  The difficulty is deciding which things are God’s and which Caesar’s.

One thing that belongs to God is forgiveness. Not the self-indulgent maudlin corporate forgiveness of those who have next to nothing to forgive, but the painful personal forgiveness that God requires of each of us if we are to receive his forgiveness.

True peace also belongs in the kingdom of God and, as St. Augustine noted, insofar as it is immanent in this world, it is related to but not the same as the peace of this world:

In its sojourn here, the Heavenly City makes use of the peace provided by the earthly city. In all that relates to the mortal nature of man it preserves and indeed seeks the concordance of human wills. It refers the earthly peace to the heavenly peace, which is truly such peace that it alone can be described as peace, for it is the highest degree of ordered and harmonious fellowship in the enjoyment of God and of another in God.

So, as a citizen of both kingdoms, it is a Christian’s responsibility to further the peace of the kingdom of heaven and of this world. Not, however, as many half-baked clerics. They have chosen to be the citizens of a third kingdom: the foggy land of interfaith diversity where earthly peace has supplanted its heavenly counterpart and is supposed to arrive wafting gently on waves of dialogue, candle lighting, mutual back-patting and ecumenical peace quilting.

The Biblical way for a state to maintain peace is by the sword: in other words, through force or the threat of force (Romans 13:2-5). It may appear contradictory to love an enemy while being required by the state to kill him, but it isn’t. As C. S. Lewis put it in “Mere Christianity”:

Now a step further Does loving your enemy mean not punishing him? No, for loving myself does not mean that I ought not to subject myself to punishment even to death. If you had committed a murder, the right Christian thing to do would be to give yourself up to the police and be hanged. It is, therefore, in my opinion, perfectly right for a Christian judge to sentence a man to death or a Christian soldier to kill an enemy. I always have thought so, ever since I became a Christian, and long before the war [WWII], and I still think so now that we are at peace. It is no good quoting ‘Thou shalt not kill.’ There are two Greek words: the ordinary word to kill and the word to murder. And when Christ quotes that commandment He uses the murder one in all three accounts, Matthew, Mark, and Luke. And I am told there is the same distinction in Hebrew…

When soldiers came to St John the Baptist asking what to do, he never remotely suggested that they ought to leave the army: nor did Christ when He met a Roman sergeant-major – what they called a centurion. The idea of the knight – the Christian in arms for the defence of a good cause – is one of the great Christian ideas. War is a dreadful thing, and I can respect an honest pacifist, though I think he is entirely mistaken. What I cannot understand is this sort of semi-pacifism you get nowadays which gives people the idea that though you have to fight, you ought to do it with a long face as if you were ashamed of it. It is that feeling that robs lots of magnificent young Christians in the Services of something they have a right to, something which is the natural accompaniment of courage – a kind of gaiety and wholeheartedness…..

We may kill if necessary, but we must not hate and enjoy hating. We may punish if necessary, but we must not enjoy it.