A book came out last year that ought to be required reading for anyone presuming to hold an opinion about whether Western powers should support the crumbling Iraqi army in their desperate efforts to halt the advance of Islamic State on Baghdad. (Not seen it put that way before by the Christian commentariat? Well, who'd have thought it?)

The book is Military Chaplaincy in Contention: Chaplains, Churches and the Morality of Conflict (ed Andrew Todd). It's a series of essays written mainly by serving chaplains who have experienced at first hand the dense moral texture of warfare. They, and in many cases the soldiers, sailors and air crew among whom they minister, have engaged in deep reflection on matters of life and death. Their context is battle, and the knowledge that the decisions made in battle are fraught with eternal consequences. This is theology at the sharp end.

Perhaps I'm wrong, but it's this element of genuine, costly engagement that seems to me to be lacking from much of what's written about Christians and war. For instance, Joe Haward for the Baptist Times argues for a non-violent response to IS. "We can go and bomb them of course, but bombing them does not destroy their ideology, rather it simply reinforces it, nurtures it, develops it and acts as a fertiliser to grow it." IS fighters "need to be stopped, but they will not be stopped through bombs because their ideology will live on".

Or here's an article by Ekklesia's Symon Hill condemning "militarism" and concluding: "You and I do not need to be at war. Despite the dominance of militarism, the first step to ending something is to refuse to participate in it."

On Christian Today, the estimable Jonathan Langley poses "five tough questions to ask ourselves" before offering our support. They are the right questions, but the answers are framed to lead to the same conclusion: that we are better Christians, more authentic followers of Jesus, occupiers of a morally higher ground if we say "not in my name".

Frankly, I don't buy that. Let's be clear: there are all sorts of reasons why bombing IS might be a bad idea. Of course it might radicalise Muslims in the UK. Of course it won't win the war by itself. Of course it just might not work and IS might take Baghdad anyway. Of course there will be – and already have been terrible and tragic consequences from the use of not-so-smart bombs. Anyone who thinks that you can wage war at any level with a clear conscience has just not been paying attention. And let's be clear, too, that Christians have no better answers, as Christians, to questions of military tactics and strategies, than any other armchair warrior: our expertise is in right and wrong, not in geo-political cause and effect.

But let's be honest, too, about what you're saying if you don't think military support – whether from Britain or America – is "Christian". While you are keeping your conscience clean, saying "not in my name" and urging dialogue, tolerance, understanding and loving non-violence – all from a safe distance – Shia women are being raped, Yazidis are being beheaded, old people and children are being forced into the mountains to die of hunger, thirst and exposure. Christians who refuse to convert or pay a sort of spiritual "ransom" are being executed. And according to some accounts – it's all a bit murky, but what do you expect when a country is imploding? – Islamic State is just a few kilometres away from inflicting these horrors on Baghdad, a city of around 7 million people.

So I wonder: if you are among those prepared to apply the words of Jesus about turning the other cheek to this situation – and others like it – would you be willing to say in person to those Yazidis, "Sorry, but I'm afraid our consciences take priority over your lives?"

Hey, it's complicated, I know: but that doesn't sound like any kind of moral high ground to me.

And that's the point. In situations like this, there isn't any high ground. It's a flat plain, with the occasional hillock. The binary "war is bad/peace is good" dichotomy just doesn't exist here, if it ever does. It's not as if two groups of reasonable people have tried to sort out their differences around a negotiating table and gone to war over clause 8b of sub-section VI. That would clearly be wrong, but this is beyond that. Trying to understand a landscape so desperately confused in terms of ethical certainties, high principles and conspiracy theories is not only futile but potentially ruinous. It leaves the victims of oppression and murder defenceless.

What's the alternative? Nothing easy – and that's why that book about military chaplaincy is so important. It shows the military enterprise not as a morality-free zone, but on the contrary, as an area of intense moral engagement, in the context of a mature, honest and painful admission: that there are times when men – and it is usually men – who are bent on violence simply have to be stopped, and that the only way to stop them is to become complicit in that violence. Those who are prepared to pay that moral price hope for grace. But those who aren't have no right to look down on them from some imagined height. If anything, those who are willing to struggle through a pathless moral wilderness because they believe it's right deserve rather more respect.

Christians are right to want to ask questions about war. As Jonathan Langley says, "We need to be the hardest people to convince that violence is the answer." It's never the answer. But sometimes, sadly, it's part of the answer.

Mark Woods is a Baptist minister and a freelance writer.