There was, of course, something very special about the House of Commons debate on Syria earlier this month. The moral challenge of how to face those who embrace evil without limits, the long shadows and sombre memories generated by military actions past, the divisions within parties and between friends, the wrestling with conscience that brought good men and women close to tears. The importance of what the House of Commons was being asked to authorise inspired outstanding speeches, most notably of all, Hilary Benn’s.

While I was listening to the shadow foreign secretary, I noticed a hunched figure in the gallery also held spellbound by the speech, his head occasionally nodding in silent and respectful appreciation.

The attentive listener had, himself, spoken earlier in the day. On the same question. Not in the Commons but in the Lords. Where he had explained, with great lucidity and authority, that Islamic State would not be defeated by military action alone. The temptations of religious and political extremism also needed to be countered with a more robust ideological response, and supporters of Islamist extremism, in particular in states such as Qatar and Saudi Arabia, had to be confronted.

That speech, just four minutes long, was remarkable for its intellectual depth and courage. What might seem more remarkable, to some, is that it was given from the bench of bishops. The Church of England — for so long caricatured as morally relativist, ethically vague, painfully politically correct and timorously unassertive — has found a new, clear, strong and resonant voice. And to the church’s great benefit, that voice belongs to the Archbishop of Canterbury.

Justin Welby may not appear, at first acquaintance, to be your archetypal Christian soldier. Slightly built, bespectacled and balding, he looks far more like a gentle clerk in holy orders than a turbulent priest. But he has shown, repeatedly, that he is willing to stand his ground and fight for Christian beliefs, taking on those who want to push faith to the margins of our society.

Most recently, he directed a blast of controlled derision towards the country’s cinema owners, who had banned a 30-second advert in favour of the Lord’s Prayer on the basis that a call to forgive our trespasses as we forgive those who trespass against us was dangerously inflammatory and might cause unacceptable distress.

When I met the archbishop earlier this month to discuss life and faith, he was still bewildered by the film industry’s decision, but inclined to see the positive side — the ad had generated millions of hits on YouTube.

But wasn’t the decision to ban the ad evidence that the church could be marginalised in a way that would have been unthinkable a generation ago? Wasn’t it proof, I asked, that in the contemporary clash of ideas Christianity was at a disadvantage?

The archbishop answered with a gentle but unflinching commitment to orthodox Christian belief: ‘No, because in the clash of ideas, Christians believe in the sovereignty of God. We are confident in the Victory of God which is seen — surpassing evil — in the events of the Cross, of the Resurrection and the Ascension.’

After decades of front-rank Anglican clerics trying to meet secular critics halfway by diluting traditional beliefs, there is something refreshing about the archbishop’s orthodoxy. But while that confident statement of Christian belief might have been a mainstream position for most of the past 2,000 years, aren’t we now in an age of retreating faith?

‘I think the tide is turning in this country. We are seeing many churches growing and particularly I would say that in the last seven or eight years one of the most exciting things has been that, in the aftermath of the Great Recession, we have seen the churches more active in social structures again, in the social events of this country, than at any time since 1945.’

That social involvement — from support for food banks to providing a welcome for refugees — has been interpreted by some critics of the church as evidence of a leftward political drift. But the archbishop adamantly rejects the idea that by following Jesus’s example Christians are endorsing any party political agenda.

‘As a Christian I don’t think you fall within the political spectrum. There was a very remarkable Roman Catholic bishop who once said, “When I work with the poor they call me a saint; when I ask why they’re poor they call me a communist.” ’

Acting to help the poor, the outcast, the forgotten and the vulnerable, the dispossessed and the despised is a Christian duty, the archbishop believes. But the Christian analysis of how to rescue those in need certainly doesn’t sit neatly on the left-right axis.

‘Catholic social teaching describes the family as the base community in society. If you say that, oddly enough, everyone thinks you’re on the right. But if you say we have to ask why, in a modern society, food banks are necessary on the scale that they are at the moment, then you are immediately on the left. Then you say, “I believe in an educational system that teaches eternal values” and they say, “Oh! He’s really on the right.” You don’t fit — so I’m not going to fit.’

One place where the archbishop did fit in was Holy Trinity Brompton, the capital’s — indeed the country’s — leading evangelical church. Sandy Millar, the charismatic vicar of HTB, who has been one of the most influential evangelical Christians of the past 30 years, helped prepare the archbishop for ordination. Evangelicals in the HTB mould tend to have traditional views, not just on theological issues, but also on sexual morality.

Few questions have so preoccupied the Anglican communion recently as the morality of sexuality — homosexuality in particular. Traditional Anglicans — whether in Nigeria or Nottingham — have been wary, at best, of the acceptance and welcome given to gay men and women and their sexual choices by secular society. It would be a challenge for any Archbishop of Canterbury to accommodate both the concerns of the traditionalists and the evolving views of the rest of British society. But when I ask this, Archbishop of Canterbury he doesn’t prevaricate.

If one of his own children were to be
gay and fell in love with another person of the same sex, and asked his blessing, how would he react? ‘Would I pray for them together? You bet I would, absolutely. Would I pray with them together? If they wanted me to. If they had a civil service of marriage, would I attend? Of course I would.’

But, I challenged him, conscious of what many evangelicals believe, wouldn’t you say to them that while you love them, their relationship was sinful or inappropriate?

‘I would say, “I will always love you, full stop. End of sentence, end of paragraph.” Whatever they say, I will say I always love them.’

Listening to the archbishop, you get the sense that he is never calculating who might be offended, or attracted, by his words. He is following what he believes to be the path that Jesus has called him to take.

But if that makes the archbishop seem austere and otherworldly, then I do him a disservice. He has an attractive, almost mischievous, giggle in his voice when talking about the peculiarities of living in Lambeth Palace, his love of CSI: Miami and the way in which the ban on his Lord’s Prayer advertisement made it an underground hit in the same way as Radio 1’s censoring of Frankie Goes to Hollywood made ‘Relax’ a surefire No. 1.

And discussing popular culture with the archbishop he lets slip that his favourite ever TV series — his ‘addiction’, as he puts it — is The West Wing.

Connoisseurs of the US political drama will recall that the pivotal episode in the series comes when advisers to President Bartlet, conscious that caution and timorousness in the face of the opinions of others has diminished his authority, urge him to be true to himself. ‘Let Bartlet be Bartlet’ is the demand.

For Justin Welby, the lesson appears to be clear. Don’t worry about what others might think, don’t tailor your views to the demands of the moment, don’t allow your conscience to be qualified or your heart to be misled. Constancy in faith is the great virtue.

I ask, on that basis, who are the archbishop’s heroes? From whom in history does he draw his inspiration? One name stands out. Revealingly, it is not an obvious name that sends a popular signal, but a figure obscure to most, not an Anglican celebrity but a Catholic martyr, not a European mover and shaker but a voice from the developing world, not a power in any land but a suffering servant.

‘Cardinal Van Thuan spent 13 years in a communist prison after the fall of South Vietnam. He was in solitary confinement. But he led his torturers to Christ. He converted, taught, and ordained priests in prison. He breathed in the presence of Christ.’

There aren’t many contemporary Christian leaders who are both energetic in their condemnation of the crimes of communism and robust in their analysis of the evil of Islamism, but Justin Welby stands out. There is something special about him. And his candour, commitment and kindness are gifts in which all can share this Christmas.