THE 2000 shows that make up the Edinburgh Fringe Festival are not there by invitation. Anyone with the confidence to gamble his or her life savings against getting an audience may perform. The result is a melting pot in which the themes and theatrical styles that will dominate the nation's cultural life over the next year first bubble. The clearest theme to emerge in the 2012 Festival is the quest to find meaning in the face of life's severest tests when religion no longer provides certainty or consolation.

Oh, The Humanity consisted of five short plays by Will Eno showing people in company but alone, flinging optimistic words into desperate situations. We met a football coach persuading a press conference that his team's lamentable season had been a good thing; two lonely hearts trying to make hollow lives sound worth while for a dating website; and an airline spokeswoman frantically putting a good spin on terrible news (funnier than it sounds in Lucy Ellinson's terrific performance).

The festival hits Bullet Catch and Bravo Figaro! also confronted audiences with their mortality, but left them exhilarated. In the former, Rob Drummond recounted the history of the famous illusion in which a conjuror catches a bullet between his teeth. He told the story of those who died attempting the trick, but it was at the same time a meditation on how we are able to pretend that our lives are ordered, even when confronting despair. By the time he invited an audience member to shoot him in the face, the tension was almost unbearable.

Mark Thomas's Bravo Figaro! told the story, funny and moving, of his father's decline from a degenerative disease. Clearly not a pleasant man, he had a passion for opera. Thomas organised a concert in the bungalow in which he lived in painful indignity; it was both an undeserved gift and a goodbye. What is it in our humanity that makes us want to do such things?

The Festival of Spirituality and Peace is one of the places where one would hope to find a vivacious Christian presence. Now in its 12th year, it has commissioned a full programme of talks, performances, and music, seeking an audience alongside the best of the rest of the Festival. It is laudably ambitious, but its ambition outstrips its achievement.

Grace, its most prominent play on a Christian theme, was poor fare. Two angels watched the story of redemption unfold as the stories of five biblical women were told. Venturing into the territory of grief, childlessness, and illness, M+E Theatre addressed themes explored by other Festival plays, but without saying anything cogent to a contemporary audience longing for meaning. In each case, God just worked another miracle. Some sparky children raised a smile, but couldn't disguise the feeling that an all-age drama workshop was cruelly exposed to a paying audience.

This review launches a distress flare in the hope that Christians will rise to the challenge of bringing performances to the Fringe that allow the gospel to speak into the yearning that is being expressed. This year's most popular shows prove that an open-minded audience is there, if you have the imagination.

A significant development of the past few years has been the rise of the Free Fringe. These are not performances by buskers, but are publicised, and in indoor venues. It's a rediscovery of the idealistic spirit of the Fringe, now widely criticised for being over-commercialised and over-priced. With more than 500 shows in that category, the Free Fringe has increasing clout, and there will be pressure to include free shows among the award-winners. So considerable has it become that two rival organisations have taken responsibility, each declaring the other unfaithful to the original ethos. They have all the right instincts to start a religion.

With his tongue-twisting poetry, Harry Baker seemed taken by surprise at receiving outstanding reviews. His poems about how to live in a man's world when you don't conform to any of the stereotypes are full of shy charm. He provided the most unintentionally funny sequence of the Fringe when trying to explain to his father, arriving late in the venue, why he had stripped to a pink hoodie and yellow tights. The most intentionally funny sequence was the other 49 minutes of his performance. It is the last time anyone will see him free of charge.

Halfway through the Festival, no one act was emerging as the most likely winner of the Edinburgh Comedy Award. Sam Wills, better known as The Boy With Tape On His Face, was the most talked-about comedian, and one of the few whose shows were selling out. While others volubly blamed the Olympics, the recession, or the Free Fringe for empty seats, his show was wordless. It relied on members of the audience being given household objects and slowly working out what he wanted them to mime. It is unusual for audience participation to leave those involved feeling so uplifted at having been chosen.

Other comedians breaking free from the pack were those whose shows had something definite to say about their themes. Alfie Moore's I Predicted a Riot trod a fine line between satire about policing and his need to keep his job as a sergeant in the Humberside constabulary. In The Racist, Trevor Noah's jokes about coming of age in post-apartheid South Africa had a quiet delivery and an uproarious response.

South Africa also provided the setting for Mies Julie, a new translation of Strindberg's play. So steamy was it with transgression, sex, and oppression that the audience all but poached. Ferocious performances from Cape Town's Baxter Theatre made this the metaphorical hottest ticket in the literal hottest venue. It had a bloody end, in which John walked away from his mother in her blue and white Mothers' Union uniform into a compromised future. That image summed up the world-view of this year's Festival.