Brandan Robertson is 23 years old and describes himself as a "spiritual entrepreneur". A Bible college graduate, he's a minister, public theologian and a commentator and activist on issues of faith, politics, spirituality, sexuality and social justice. He's written for TIME, The Washington Post, Patheos, Sojourners and The Huffington Post among others.

He's also a controversial figure among evangelical Christians, many of whom would flatly deny his claim to be one of them. 

As "a good evangelical Christian who felt called to be a pastor", Robertson's life and career plans were turned upside down at Moody Bible college when he began to experience feelings of same sex attraction. The strong 'black and white' beliefs that he had previously held on sexuality and faith were shattered.

For many, his affirming attitude to same-sex relationships puts him automatically outside the evangelical fold – and endorsements from Brian McLaren and Rob Bell, who have both strongly affirmed the validity of same-sex relationships, have confirmed their verdict. He's also been a spokesman for the Evangelicals for Marriage Equality campaign and is an increasingly high-profile advocate for the LGBT cause.  

It's because of this that his book Nomad: Not-So-Religious Thoughts On Faith, Doubt, and the Journey In Between was dropped by publisher Destiny Image, which includes in its basis of faith the statement: "We do not condone, encourage, or accept the homosexual lifestyle. Destiny Image renounces this lifestyle as ungodly and completely contrary to the Kingdom of God." 

Robertson is in the UK to promote a revised version of Nomad, described as part autobiography, part Christian spirituality and as a powerful call to inclusivity.

Nomad – why the title?

It's been with me ever since I began writing it. It describes how I feel and how my generation is feeling, wandering not only spiritually but through life in general. The millennial generation is a generation of nomads. They didn't grow up within a tradition.

There are downsides to that. I'm optimistic about millennials, as I'm one of them. But we're rediscovering tradition, rediscovering roots. Young evangelicals aren't going to megachurches, they're going to Anglican, Catholic and Orthodox Churches. They're putting their spiritual journey into broader narratives. But the danger is that they'll just wander.

What is it about traditional churches that attracts them?

The free church movement in the US, and the Puritan tradition, was always about breaking off from tradition, being authentic, expressing faith in an individualised, localised way. That reached its peak in the megachurch tradition. But that became very disconnected. They have their own music, their own teaching, their own doctrine. On the one hand that's very appealing to the consumerist, individualist mindset of the West. But the beauty of the liturgical tradition is that it gives us a rhythm and a contour to our lives. A lot of megachurches are embracing liturgy now. Willow Creek has a full liturgical service every Sunday evening.

You're happy to identify as an evangelical, though you hold some positions that aren't typical of evangelicalism. How do you define it?

If you study the history of the evangelical movement, it really means to be a moderate, middle gound faith, between fundamentalism and liberalism. But fundamentalism rebranded itself as evangelicalism. My passion for the last six years has been to reclaim that. The historic definition is David Bebbington's; he talks about crucicentricism, biblicism, conversionism, activism and evangelism. I differ from quite a lot of conservative evangelicals, but I still believe all of that. The gospel is good news for humanity. I'm reluctant to distance myself from that label. It's the tradition I identify with – I connect best in worship with 4,000 people singing Hillsong music.

Your book isn't just about sexuality. Talk to us about its themes?

It's almost not about sexuality at all. In the orginal manuscript that was only two sentences. Now it has one chapter, not bashing conservatives, but an exploration of how sexuality is one of several things that are fluid, morphing and changing. It's a call to recognise that this is all part of our conversation with God.

Nomad is a series of reflective essays reflecting on the different lessons I've learned on my spiritual journey. I talk about roots, about rediscovering liturgy and ritual, experience as an authoritative source for life, war and culture wars – we're not called to be warring against the culture. So it's a number of 5,000-word essays that dig into things my generation is looking for in spirituality, that may or may not be in the Church right now.

Is there an appetite in our culture for a different way of doing religion?

Absolutely. I dedicated Nomad to Phyllis Tickle, who wrote extensively about how every 500 year mark leads to a new reformation. There is now a decline of the church establishment but an increase in spriituality. Statistics across the board show an increase in spirituality, an opennes to wonder and mystery, while organised religion has fallen apart. We are distrustful of what power and heirarchy represent.

But there might be pain along the way if people feel traditional views of sexuality are threatened?

My heart goes out to conservatives. There are a large number who truly believe that that's what God requires – and it's not because they are hateful homophobic bigots. But Jesus said, "When I go from you I will send my Spirit, who will continue to reveal truth."

We are called to abandon fear of change and open ourselves up to the Spirit. That doesn't mean conservative churches should necessarily become LGBT-affirming, but they should be open to experience God wherever He's working. If conservatives can open their churches allow LGBT people to be part of them, knowing a person face to face can change their hearts and minds. The only place I have seen unfaithfulnessness is when people aren't open to what God is doing in the lives of LGBT people.

Brandan Robertson is touring the UK and Ireland until June 20. Nomad: A spirituality for travelling light is published by DLT, price £12.99.