The Prime Minister has in recent times been prepared to shift some moral ground for political ease. Now he faces the greatest moral test of his short time in power in the face of calls for an inquiry into the O'Donnel raid

I can't help wondering if Bill English is going to church on Sunday. While reports today say the Prime Minister is meeting with Defence Minister Gerry Brownlee and New Zealand Defence Force heads about the claims in the Nicky Hager and Jon Stephenson book Hit & Run, the more crucial meeting that day may be between English and his God.

The book outlines a raid, allegedly led by New Zealand's SAS; a raid then-Defence Minister Wayne Mapp has since called a "fiasco". It's a word that carries some weight in this context. It's the title of one of the definitive books on America's misadventures in Iraq at the same time as the war in Afghanistan.

Hager and Stephenson's book, Hit & Run, looks at New Zealand's own misadventure. Not a whole invasion, but a single raid on a single village, Khak Khuday Dad, in August 2012. It was a search for insurgents responsible for the death of Lt. Tim O'Donnell, a Kiwi soldier killed 19 days earlier. It seems, however, on the authors' evidence, that the raid went wrong. The insurgents weren't there, six villagers were killed and 15 injured.

This version of events was backed up Friday, by David Fisher in the Herald, quoting an SAS source confirming that civilians were killed. The source says, specifically, that New Zealand marksmen killed two of the victims.

At the time a report by the international coalition commanders in Afghanistan, ISAF, and the Afghan govenrment said no civilians were killed. Further reporting has suggested otherwise and Mapp seems to accept now that innocents died, although he believes the soldiers thought they were under attack and merely opened fire because they thought themselves at danger.

Of course that raises questions as to why the troops should have been there at all; can you really claim any form of self defence or that the deaths were "an accident" if you are attacking a village?

It's just one of the questions that make calls for an inquiry impossible to dismiss. Another is why the Defence Force (and in lock step, the government) insists on standing by its 2011 statement that no civilians were killed in the attack – by New Zealanders or others – in the face of Mapp's acceptance and such detailed reportage by the authors.

Earlier in the week, I described the interview with Wayne Mapp that first revealed this raid took place. On Friday I watched the Q+A panel that aired afterwards. It was remarkably prescient. Political scientist, Dr Jon Johansson said "logic" demanded that this attack, so soon after O'Donnell's death, was a "reprisal attack" and therefore was a stain on New Zealand's proud military tradition.

Johansson went onto quote John Key from January 2010, saying "New Zealanders deserve to know what our forces are doing overseas.”

Host Guyon Espiner went on to ask what has become another key question. What involvement did the New Zealand government have in this and did the raid have then-Prime Minister John Key's approval. Hager and Stephenson say he directly gave the go ahead. So precisely how much did he know and what did he expect of that raid?

These were questions being asked the very day that first interview aired, and surely now, six years on, answers are required. If Key – and this government – were serious about that 2010 promise of greater transparency around the SAS.

It is now down to English to make what the Australian's describe as "a captain's call".

While English is known to most New Zealanders as the fiscal rock on which the fifth National government has been built, in many way he's also its moral compass. It was he who has looked for new solutions to welfare dependence and who took the stand that increased spending on prisons was a moral failure. It was he who show discomfort at John Key's hair-pulling. He has taken moral stands, guided by his faith, on issues such as abortion and gay marriage.

My question this weekend is whether he can look at an innocent man hanging on a cross, suffering for the sins of others, and not think about three year-old Fatima, who died in the raid on Khak Khuday Dad through no fault of her own. Whether he, like Pope Francis, can say “faith and violence are incompatible".

As Finance Minister he had some freedom to follow his conscience. As Prime Minister we've already seen him back away from his previous position on gay marriage, seemingly for political gain. He's gone from calling prison spending a moral failure, to record prison numbers and budget increases.

So this is now a critical moral conundrum for a man who has for so long let his faith guide him on matters of conscience.

How does he approach this decision? What now? Many are saying he has the political space to demand an inquiry, because he wasn't in charge then. But it's not that simple. As deputy Prime Minister, we can expect him to have been briefed to some degree on these matters. What did he know at the time and what has he held back all these years? When did he know about the alleged civilian deaths and what did he do with that information, if he did know?

But more to the point, English will be under immense pressure from the stonewalling NZDF. Standing beside Key when he promised more SAS transparency was Lt-Gen Jerry Mateparae. He's now Sir Jerry and Governor-General.

Can English open up an inquiry that could impugn the country's Governor-General, perhaps even raise the question of war crimes around him? For the book claims Mateparae was there on the ground with Mapp, when approval was sought from Key, and he watched the raid play out.

Has he been honest with his political master and the New Zealand public? These are obvious questions raised by this book, but there is huge political pressure on English not to ask them.

English is in a very uncomfortable place with this decision; reputations of important people hang in the balance. This is a true test of his moral fibre, of his courage under (political) fire. And in a very real way, of his faith, and its central tenets of concern for every child made in God's image, truth and justice.

And ew Zealanders will be wondering: Do we get to know what our forces are up to overseas, or not?