Humanists are often accused of being negative. We know what we don’t believe and are only too quick to demolish the fanciful ideas of those who profess a faith, just as AC Grayling does in his ruthless dissection of the argument for Intelligent Design. But what should we put in the place of religion? This issue offers a range of alternatives.

While humanism derives its morality from human nature and a commitment to human rights, Paul Heelas, Professor of Religion and Modernity at Lancaster University, warns that this is not enough: humanity craves a spiritual dimension. Rather than scorning those who are seeking a sense of the sacred, he says we should learn to understand this aspect of ourselves and to incorporate it into our worldview.

Tony Blair would certainly agree, since understanding and mutual respect are at the core of his new Faith Foundation. It’s the latest in a long line of initiatives aimed at bringing together opposing religions in an attempt to dissolve differences and oppose extremism. Edna Fernandes speculates on the hazards of mixing religion and politics.

But, according to American philosopher Ron Aronson, no morality makes sense without politics. He tells Doug Ireland why he believes that atheism must be coupled not merely with a sense of equality and rationalism but with a commitment to socialism.

Political or religious ideologies frequently founder not just through obdurate fundamentalism but its cellmate: lack of trust. Africa expert Richard Dowden introduces a community which does manage, across the world, to maintain its devotion to peaceful unobtrusiveness, combined with a unique trust-based economic system. The Mourides of Senegal represent a thought-provoking example of how religion can inspire a benign social and economic force.

More often, though, it can be deadly, and its tactics insidious. In our cover story Dagmar Herzog reports on the latest propaganda strategy of American evangelicals. They’ve finally caught on to the joys of sex – with a few provisos, naturally.

In the endeavour to replace faith with evidence, rationalists naturally place great emphasis on vision. We want to see for ourselves. But appearances can be deceptive, as experimental psychologist Richard Gregory argues, in his exposition of the role of the brain in visual perception.

Francis Bacon, whose major retrospective opens at Tate Britain this month, is widely celebrated for his raw, brutal representations of the human condition. But Owen Hatherley reassesses the relationship between the artist’s work and his messy, tragic life.

For the final word on the human condition, Martin Rowson manages to sum up the history and future of the world with one word: and it’s not “faith”.