Cain, By José Saramago, trans. Margaret Jull Costa

Abel and Cain have each made an offering to God. Abel's is accepted, Cain's rejected. In a fit of jealousy, Cain murders his brother. When God asks where Abel has got to, Cain replies tetchily, "Am I my brother's keeper?" God discovers the murder, and Cain is punished. He will live, but he will be forever marked, and condemned to wander the earth.

In the late José Saramago's final novel, Cain's wanderings take him through some of the greatest hits of the Pentateuch. He appears, Zelig-like, at the walls of Jericho just before the trumpets sound, he's there among the impatient crowds waiting for Moses to descend from Sinai. When Abraham is about to sacrifice Isaac, Cain is standing there beside him. Actually, it's Cain who saves Isaac's life, whatever you may have been told by less reliable sources.

Cain wanders from one present to the next, usually not quite in control of his improbable trajectory. He is even aboard the ark with Noah's family. The preparations for the launch will lead to an argument with God about Archimedes.

Saramago's Cain is a murderer – as it turns out, a mass murderer – but also "essentially an honest man". He's an innocent, in a world ruled over by a God who is thuggish, petty, unreasonable and jealous. This God has some greatness but is constantly compromised – uniquely rich and supremely powerful and very good at mental arithmetic, but tiresomely stymied by the laws of physics. He's ineffable, rarely seen, but when he does appear he appears trivialised by banal details. Worse – he's a god whose behaviour towards his creations is often no better than "wickedness". The kind of god, remarks Isaac, who would order a father to kill his own son. It is only Cain, who recognises the lord for what he is, and - unlike Abraham, unlike Job - dares to challenge him. The lord is not amused.

Readers of Saramago's controversial The Gospel According to Jesus Christ will recognise the irreverence here, but there is more to his anachronistic unpicking of the Old Testament than a mere wish to shock. The assault on all these stories we seemed to know - undermined sometimes in narrative details, sometimes merely in tone - is a subtle and not-so-subtle challenge to what he calls "the official history".

Saramago is a first-person narrator who keeps himself just out the corner of your eye. He's often funny, and thought-provoking, and delightfully mischievous, savouring the details of his own defiance. Every little barb, every little twist is absolutely deliberate. Translator Margaret Jull Costa carefully holds the thread of his winding sentences, which snake across pages and pages, running right through the direct speech, one sentence sometimes covering entire, fully-realised arguments and half a dozen switches in register, one moment Biblical-stately, the next earthy and idiomatic. The lord is glorious, magnificent, almighty, eternal, splendid, and also just a son of a bitch.

Cain was composed shortly before Saramago's death last June aged 87. It's apparent just how his ferocious intelligence and argumentative atheist glee still blazed. And it's impossible to imagine he didn't relish the writing of it.

Daniel Hahn is interim co-director of the British Centre for Literary Translation, Norwich