Jesus: Uncovering the Life, Teachings, and Relevance of a Religious Revolutionary is a book that should have begun with its epilogue. It is at the end that Marcus Borg makes clear what is at stake for a 21st-century treatment of the historical Jesus and why it matters. You don't have to be a devout Christian, nor the least bit conversant in all the religious jargon, to grasp the importance of a book like this. But those who have no acquaintance with the nuts and bolts of basic Christian thinking are unlikely to wait until the final section to discover the rationale.

And this is unfortunate, because the conversation has gained urgency. Today, powerful groups are making claims in the name of Jesus – claims that are moving us to the brink of extinction. For those of us who want to bequeath to our children a decent world, we may have no choice but to say "No" to Jesus, or at least to a particular version of Jesus. We cannot afford to be complacent about the activities of those who think it honorable to be instruments of an apocalypse. If we are to oppose these activities, then we must begin by educating ourselves about how the Jesus story has been manipulated – which claims are plausible, and which are sheer nonsense. And, as Borg makes clear, there are many that are nonsense.

Borg's writing falls within the genre that Albert Schweitzer laid down a century ago when he published The Quest of the Historical Jesus. There, Schweitzer summarized all the historical scholarship that had preceded him, and established a footing for the 20th-century quest to begin. This turned out to be a great gift because, by the middle of the 20th century, the quest had gathered new life with the discovery and translation of documents at Qumran and Nag Hammadi. These have given us more material to refine our view of the life and times of Jesus.

The genre is problematic. Is it history? Is it theology? Or a mix? If we weight our thinking in favour of one discipline or the other, how useful will it be in answering the extremists who use Jesus to achieve pragmatic goals? If we lean towards history, as Borg often does, then -- so the argument goes — we can demonstrate that the historical Jesus lived in a way that can't possibly speak to today's highly polarized debates about American imperial aspirations and public school curriculum in Kansas and stem cell research. If we restrict our examination of Jesus to a 1st-century peasant living on the margins of the Roman empire, then we can easily limit his teachings and meaning to that context while looking for better tools to deal with the many crises which were unimaginable in that world.

But there is a problem with history: it's — well — all in the past. I don't mean to sound cute. It's simply that, of all the academic disciplines, history has proven least receptive to recent intellectual developments. Part of the reason for this lies in the nature of history itself. Because we don't have time machines, first–hand observation is impossible. This rules out modern scientific method as an approach to understanding historical events. If I want to know whether a balloon contains helium, I let it go and watch it rise or fall. But there is no such hands–on approach to doing history. Apart from strict empiricism, the only other scientific approach I can use is statistical modeling.