It was significant in my own development because at the time I read it, I was still largely pacifist. That pacifism had been weakening under the force of affection for heroic fantasy, including the somewhat-historical Arthur. I was able to keep the two separate with a juggling act between clear justice of fighting orcs or Mordred versus the morally ambiguous wars of modern history. A highly permeable wall, but that's what I had.
Lewis's reasoning was not unassailable - few mortals have ever constructed a bulletproof argument on any subject - but it included approaches I had not considered and distinctions I had not made. He resorts to false dichotomies in at least two places, but even so, these only weaken his conclusions - they do not overthrow them.
But that's not what I came to talk about. For those of you who have the text, I uncovered something else about it: the distinctions about good and evil, and the command of Jesus to turn the other cheek in the context of the rest of Scripture (including some of his own statements) and the writing of Christians from that time to this, apply to other moral topics. I first saw parallels with immigration arguments, but once the possibility of reapplying the reasoning came to me, charity, loyalty, and obedience to authority all came into play as well.
I'm not sure this one is the best example of the argument, but it is a great quote, and reasonably related.
It may be asked whether, faint as the hope is of abolishing war by Pacifism, there is any other hope. But the question belongs to a mode of thought which I find quite alien to me. It consists in assuming that the great permanent miseries in human life might be curable if only we can find the right cure; and it then proceeds by elimination and concludes that whatever is left, however unlikely to prove a cure, must nevertheless do so. Hence the fanaticism of Marxists, Freudians, Eugenists, Spiritualists, Douglasites, Federal Unionists, Vegetarians, and all the rest. But I have received no assurance that anything we can do will eradicate suffering. I think the best results are obtained by people who work quietly away at limited objectives, such as the abolition of the slave trade, or prison reform, or factory acts, or tuberculosis, not by those who think they can achieve universal justice, or health, or peace. I think the art of life consists of tackling each immediate evil as well as we can. To avert or postpone one particular war by wise policy, or to render one particular campaign shorter by strength and skill or less terrible by mercy to the conquered and the civilians is more useful than all the proposals for universal peace that have ever been madeI think that applies to "comprehensive solutions" beloved by politicians, activists, and dreamers of many types.
Another Lewis quote, from "Learning In War-Time."
We are now in a position to answer the view that human culture is an inexcusable frivolity on the part of creatures loaded with such awful responsibilities as we. I reject at once an idea which lingers in the mind of some modern people that cultural activities are in their own right spiritual and meritorious — as though scholars and poets were intrinsically more pleasing to God than scavengers and bootblacks. I think it was Matthew Arnold who first used the English word spiritual in the sense of the German geistlich, and so inaugurated this most dangerous and most anti- Christian error. Let us clear it forever from our minds.The work of a Beethoven, and the work of a charwoman, become spiritual on precisely the same condition, that of being offered to God, of being done humbly “as to the Lord”.