Religion's status socially is under pressure – the questioning of new Liberal Democrat leader Tim Farron over his beliefs suggested an anxiety about Christian evangelism driving a political agenda, while atheism has been taken up as a badge of intellectual superiority by fans of Richard Dawkins.

But theatre has a soft spot for the ideas and language of spiritual endeavour. While there are plenty of science-orientated productions at the Fringe (Tangram, for example, are completing their 'Scientrilogy' with a musical look at the life of Marie Curie), these tend towards explaining concepts, whereas religious iconography offers a way of exploring deeper issues.

'It may be ironic for an atheist to say, but the theatre is a place of true spirituality,' says actor and playwright Bart McCarthy. 'A few times I have experienced those rare, stunning moments in which I felt myself, not as an actor, but as a conduit for some ethereal energy that transported everyone present into a higher state of being. Wondrous.'

McCarthy is performing as Satan at the Fringe: his show – Satan Speaks: 'Why I Don't Exist' – A TED-ish Talk – features live possession of the poor actor by the Prince of Darkness who tries to convince the audience that he is not real. Despite his scepticism, McCarthy uses the devil as a symbol for human culpability. 'I suppose the horror is that if Satan does not exist, we have only ourselves to blame for all the evil and depravity in the world.'

On the side of the believers, Testament is a Christian rapper, a star of UK hip hop and an enthusiast for the theology of romantic mystical poet William Blake. Working with DJ Woody and videographer Dave Lynch, Testament's Blake Remixed is an introduction to the poet that claims him as a contemporary. 'I really feel that Blake was from the street and in this culture in 2015, I feel like UK street culture is heavily hip hop influenced,' he says. 'I don't think he would be just a rapper, he'd be taking it on because he was like a self-taught Jedi polymath, I think he would be really engaged in multimedia.'

Testament's music reveals his strong spiritual beliefs, but in Blake's poetry he has found a language that allows him to apply his skills to a highly imaginative theatrical format: 'We've got twice World champ DJ Woody as our live scratch DJ … he's actually controlling interactive visuals. We got four acclaimed hip hop artists (Soweto Kinch, Ty, Jehst and Shlomo) to play characters via special films, all manipulated live by DJ Woody in conversation with my performance. So it's six hip hop artists for the price of two! Plus live beat boxing, rapping, spoken word, all new music, all with the heartbeat of William Blake.'

Another artist who finds inspiration in Christian thought is Jo Clifford. Although The Gospel According to Jesus, Queen of Heaven could be mistaken as controversial – imagining Jesus as a woman – Clifford insists she is 'completely in sympathy with most of the values of early Christianity and profoundly moved and inspired by the Jesus we read about in the Gospels.' Addressing the antipathy directed at LGBTQI people, and its roots in religious belief, Clifford's piece is making a statement for a more inclusive faith, as well as drawing a smart parallel between the New Testament's 'Man of Sorrows' portrayal of Christ and modern persecuted minorities. And it is upon the foundation of Christ's words that Clifford built her script.

'"We all have a light", the play says, and sometimes it's the very thing we've been taught to be most ashamed of. And if you have a light, do you hide it in a closet? No. You bring it out into the open where everyone can see it. And be glad it exists to shine in the world.'

But it is not just Christianity that provides a pattern for theatrical meditations. Storyteller Xanthe Gresham Knight has delved into pagan mythology for her two shows, Paradise Bride and Morgana Le Fey. Like the other artists, she discovered fertile material that has, perhaps ironically, led her away from theology. 'Goddesses embody archetypal emotions that feel as limitless as water,' she says. 'They've helped me shake off religion, which is all about limits. After being a storyteller for 20 years, all mythologies seem to me to be streams from one ocean that belongs to us all.'

If Gresham Knight has used ancient mythology to challenge her own religion, other artists invoke ideas of God not in a spiritual but a metaphorical or philosophical manner. Despite naming his show Building God, poet David Lee Morgan insists 'it is actually about science, the science of revolution. Science is in one sense the opposite of religion: the title, Building God, is a reference to what my dad used to call the infinite perfectibility of man.'

Meanwhile, in Charlie and the Philosorappers, Charlie Dupré sets up the creator of the universe in a square-go with a certain anti-theist biologist. 'During his rap battle with [Richard] Dawkins, he covers three of the main arguments for his existence, and the audience are given the vote at the end,' Dupré explains. With the show's emphasis on Scottish thinker David Hume – and featuring an appearance from the mighty German intellectual Nietszche – Dupré's God is more of an intellectual assumption than physical entity or principle worthy of worship.

In The Temptation of St Anthony, Tom Bailey was inspired by stories of a fourth-century saint, and set out to examine the relevance of his battles with demons in a contemporary society. In a production supported by the Wellcome Trust, Bailey exposes the thin line between what is now understood as a challenging mental health condition but what was once understood in more mystical terms.

Yet even among the more rational approaches to religious belief – Gresham Knight, McCarthy and Morgan all challenge the subject – the usefulness of its language and characters is evident. As Jo Clifford concludes, theatre is ideal for the discussion of matters spiritual, 'because to create good theatre around these themes they have to stop being theological abstractions and become clothed in flesh and blood.'

And Christopher Haydon, who is directing The Christians (including a full choir on stage) at the Traverse, recognises how its themes remain pertinent. 'Although the play is set within an American evangelical church – which is quite different from the kind of Christianity we have in the UK – the underlying issues about faith, community and leadership will ring true for everyone, even hardcore atheists!'

The diversity of religious imagery and traditions on display at the Fringe are a reminder of how these ancient systems are symbolic ways of examining common human experience, and the theatricality of theology can lend an intensity to what might otherwise be a dull discussion of Big Ideas. Religion may be controversial, but it suggests a smooth strategy for summoning powerful performances.