Decried as an apostate by some, praised as a prophet by others – no one divides evangelicals quite like Rob Bell. The former megachurch pastor and provocateur is the subject of a new documentary, whose title captures well the cry of Bell's despisers: The Heretic.

A trailer for the film, produced by Untold and directed by Andrew Morgan, was released this week. 'Somewhere along the way the Jesus movement got hijacked,' says Bell in the trailer in a line typical of his theology. From his perspective, that's about recovering the radical nature of Jesus' original teaching as a prophetic address to today's Church – an institution otherwise mired in pretentious, legalistic and small-minded religiosity.

Bell continues: 'The religions have failed. So we are going through a revolution because these great traditions have to be expanded.' His emphasis particularly on a socially conscious faith often at odds with conservative evangelical tendencies has seen some dismiss him as a liberal. He adds, in the film: 'Women's rights, LGBT, minorities, love of our Muslim neighbours – if those aren't all basics, we're done'.

Bell became famous as an evangelical who pushed the envelope with innovative communication and provocative ideas. He's only become more controversial over time; after pushing against several key tenets of American evangelicalism, many would say he's not even a 'Christian' any more. We might summarise his 'journey' in three points.

Bell gained notoriety when he began 'repainting the Christian faith' in his book Velvet Elvis; alongside his NOOMA video series it pushed against inherited axioms of faith and promoted in fresh and engaging style the challenge of Jesus' teaching. His following book Sex God encouraged rethinking of Christian attitudes to relationships, but remained orthodox in its teaching. Bell has frequently battled to divorce true Christianity from contemporary ties to conservative, Republican ideology and American exceptionalism. He spoke out vocally against the US war in Iraq, a controversy that divided his own church, Mars Hill, at the time.

But Bell hadn't truly ruffled evangelical feathers before the advent of his book Love Wins, which questioned traditional evangelical teaching about hell as a place of eternal conscious torment. He floated the possibility of universalism – the idea that ultimately, all are saved from judgment – and it earned him the infamous tweet of dismissal from John Piper: 'Farewell Rob Bell'.

For many Bell's final straw was his endorsement of same-sex marriage; in 2013 he declared: 'I am for marriage. I am for fidelity. I am for love, whether it's a man and woman, a woman and a woman, a man and a man...I think this is the world we are living in and we need to affirm people wherever they are.'

It put him beyond the pale of many conservatives at the time, but Bell hasn't seemed too bothered by his critics. After all, in 2011 Time magazine named him one of the 100 Most Influential People in the World.

He's increasingly moved away from an explicitly Christian context, leaving his megachurch pastor role for a series of speaking and writing projects across the US. But his preoccupation with Jesus and the Bible endures, as his 2017 book What is the Bible?, and 2018 tour The Holy Shift, suggest. Bell even has hope for reclaiming the title 'evangelical' from its political strictures.

Stalwart evangelical and committed Trump ally Franklin Graham has called Bell a 'false teacher', and of course, a 'heretic'. In the present political climate, many won't see that as such a bad thing.

The trailer for 'The Heretic' can be watched here.