Moments before our interview, Archbishop Josiah Idowu-Fearon missed a call from Sa'adu Abubakar, the 20th Sultan of Sokoto and spiritual leader of Nigeria's 70 million Muslims. As the new Secretary General of the Anglican Communion, a body of churches spread across more than 165 countries, the Archbishop is tasked with holding together an estimated 85 million Christians in unity. It's no mean task.

It might seem an odd friendship – Archbishop Josiah smiles widely as he recalls jokes shared with Abubakar and says the two "get on very well" – but will come as no surprise to those familiar with his background. Having grown up in Muslim-majority northern Nigeria with a priest for a father, Josiah became a Christian aged 14 but remained fascinated by the faith of his community. He spent a year studying Islamic civilisation at Durham University in 1976, which he says "opened my eyes to the richness in the Arab culture" and signalled the beginning of a lifelong commitment to the Muslim world.

He graduated with a degree in Theology, with special interest in patristics; the study of the early Church fathers and how they wrestled with the nature of Jesus as both fully human and fully divine. He began to see similarities between the Bible and Quran, and went on to do a Masters in Islamic Studies and Muslim-Christian relations at Birmingham University. It was then that he felt God speak clearly about his passion. "I knew the Lord was calling me [to be] a bridge builder," he says.

"I have spent the last 25 years as bishop [first of Sokoto, then Kaduna] trying to build bridges of understanding between two different communities. We are theologically and doctrinally different, and yet we've been able to work together...For me, that's what it should be."

The Archbishop's dedication to unity is evident; his face lights up as he speaks and he's incredibly animated – a far cry from any preconceived image of a droning clergyman. But he doesn't fit into the sterotype of an evangelical Nigerian pastor, either. He is amiable as we talk; inspiring hope in the future of the Anglican Communion while managing to jump between serious theological debates and joking about the superiority complex of Oxbridge students at the drop of a hat. I can't help but be encouraged that this is the man charged with holding together the Communion.

Archbishop Josiah's closeness to the Muslim community in Nigeria, however, has inspired some controversy. Having established a Centre for Islamic Studies in Kaduna at the height of the religious riots in 2000, which resulted in the deaths of up to 5,000 Christians and Muslims over the introduction of Shariah Law, he was accused of having converted to Islam, and consequently denied a second term as Archbishop. He obviously refutes the allegations – of his faith he says "my trust, everything, is in Christ, and...I've never looked back" – and has instead committed to increasing understanding between different religious communities, particularly in his home country.

As the escalating Boko Haram crisis continues there, Archbishop Josiah is insistent that touting the conflict as having religious grounds is an unhelpful narrative, driven by a false understanding of the real issues. "First and foremost, my conviction has always been this and it hasn't changed: most of these crises we ascribe to religious differences have very little to do with religion. Religion is a façade," he says.

"You can see that in the extremist reactions today, whether it is ISIS or Boko Haram...religion is a façade. What these guys want is power. They know through a democratic process they will never ever get power, so [they] latch onto religion." A better understanding of one another's religion would help the drive for peace in Nigeria, and around the world, he says. It's not about forgetting our differences and moving on, but about coming to understand them. "I think that's what we need, not only in Nigeria, but in Africa."

Here, he sounds even more like Justin Welby, whose determination to see the Church "disagree well" has become a hallmark of his term so far at Lambeth and, like Welby, Archbishop Josiah acknowledges the breadth of the Anglican Communion. "People need to know that we are not one Church," he says. While the pope has ultimate authority over the whole Catholic Church, there is no equivalent in Anglicanism, allowing room for a difference of opinion. "Divisions there have always been, and there will always be...because when you practise a religion that has its texts, interpretations usually allow room for divisions," he says.

"Therefore, there is an increasing need for understanding. If within the Communion, we have this understanding, we can live together with our differences."

Welby warned Synod last year of a "flourishing Communion but also a divided Communion" and perhaps the largest challenge facing it today is human sexuality. It's another area where Archbishop Josiah has courted controversy. He was quoted in March 2014 as telling Nigerian newspaper the New Telegraph that the criminalisation of homosexuality was "good", leading to accusations of homophobia and being anti-gay.

"Our battle today is not against homosexuals, our battle today is against those who say God's standards are not good enough for us," he said, according to the paper.

"The government has criminalised homosexuality which is good, our battle is not against human beings, it is against the devil."

Archbishop Josiah later denied making the comments. "I have never supported the law in Nigeria that criminalizes the gay community and I will never support it," he said in a statement.

"For the majority of African Christians, the Bible judges culture, including African culture. As African Christians we must accept other cultures and the way they also understand the Bible's relationship with culture. I accept and promote a culture of respect for such differences."

With a wry smile, he confirmed to Christian Today that he remained neutral during the debate about homosexuality in Nigeria's National Assembly last year. He's asked about this in every interview, but kindly insists he hasn't tired of it yet. "I never said anything for or against," he says. When asked by the press to comment on the passing of the anti-gay law, he says he remembers clearly his reply: "How I wished all that time and money spent had been spent debating and finding solutions and criminalising corruption. That in our situation, in Nigeria, homosexuality is not our problem. Our problem is corruption. How I wished. That was how I put it."

The Archbishop doesn't condone same-sex relationships, but is insistent that he is bound by Resolution 1:10, passed at the Lambeth Conference in 1998 and reaffirmed 10 years later. It positioned the Church as in favour of traditional marriage, but also committed to the belief that everyone is welcomed and loved by God.

"While rejecting homosexual practice as incompatible with Scripture, [the Conference] calls on all our people to minister pastorally and sensitively to all irrespective of sexual orientation and to condemn irrational fear of homosexuals," the resolution states. "We wish to assure them [gay people] that they are loved by God and that all baptised, believing and faithful persons, regardless of sexual orientation, are full members of the Body of Christ".

Archbishop Josiah therefore maintains his opposition to the criminalisation of homosexuality. "I don't agree with promoting that lifestyle, but I cannot criminalise anybody for it," he says, but insists that the Church "has the right to disagree with any law that is against biblical principles." Just as he opposed the anti-gay laws, he believes that the Episcopal Church in America, for example, should oppose the legalisation of gay marriage. "Christians in positions of authority and responsibility are always very timid, they allow the secular world to overcrowd them, so that fine line is missing".

Yet, despite all this, he is adamant that homosexuality should not actually be the Church's focus, but rather corruption, poverty, and religious extremism. "This question of human sexuality is down, down, down our list of priorities," he says, jabbing his finger to the floor to emphasise his point.

"We're sick and tired of it, honestly. Rather, we want to promote our values and there are values we share as Christians, Muslims and even those who have no religion. Simple, human values, and that's one thing I plan to do from this office – to liaise with the press, to help us promote common human values, so that the world will become a better place."

And as for the Communion? "My prayer to God is very simple, that I would be able to be a bridge builder; to create the culture of respect for differences, a culture of accepting people as human beings and loving them for who they are in Christ. To play down the things that divide us, that's my goal. And I hope I succeed."