It is a curious fact that the modern Hebrew for ‘atheist’, Tim Whitmarsh notes in passing, is apikoros. The word derives from Epicurus, who set up shop as a philosopher in Athens around 306 BC, but it became so domesticated in Hebrew that the medieval thinker Moses Maimonides, till he found out better, thought it was of home-grown Aramaic origin. In ancient Jewish usage, however, I think apikoros meant someone who denied that God takes care of the world, which was indeed the claim of Epicurus. Though Whitmarsh sets out to show that atheism was quite normal in ancient (Greek) history, atheism turns out to be a slippery notion.

Epicurus declared that the whole boundless world was made up of an infinite number of indestructible atoms in unpredictable motion. Our souls too were made of atoms, a tinier kind, like those that constituted wind and fire. And as Whitmarsh, a professor of Greek culture at Cambridge, explains it, Epicurus did teach that the gods existed, but were seen not by our senses, only by our minds. ‘There are all sorts of philosophical difficulties with this idea,’ he says, right enough.

At the last, he is puzzled by Epicurus’s continuing to insist on the gods’ existence despite magisterial assurances that, since the gods are not in charge, ‘death is nothing to us’. Our atoms merely disperse. So Whitmarsh puts forward the hypothesis, a little ungenerously, that ‘Epicurus might have been motivated by fear of persecution’. After all Socrates, 100 years earlier, had been executed for ‘not recognising the gods the state recognises’. But if ‘death is nothing to us’, why should Epicurus have cared?

Naturally the author is friendly to the great Roman poet Lucretius (c.100–55 BC), whose epic, On the Nature of Things, made Epicurean warfare against religion memorable. Taking the story of Agamemnon, who sacrificed his own daughter Iphigenia in order to placate the goddess Artemis, Lucretius concluded: ‘Such is the terrible evil that religion was able to urge.’ These were words that Voltaire was to quote in 1737 in urging Frederick II of Prussia to impose secularism.

Lucretius calls Agamemnon’s crime ‘impious’, and so it was if we remember that pietas in Roman thinking was first of all the duty of children to parents and vice versa. There are further paradoxes about Lucretius’s attitude to the gods. He makes Epicurus the prime example of a theomakhos, a battler of the gods — even though the gods did not exist, at least not as commonly conceived. Then Lucretius explicitly claims for Epicurus the status of a god, and to do sohe employs ‘the very poetic form traditionally associated with theology’, the hexameters in which Hesiod composed his Theogony.

After his exposition of Epicurus’s thought, one can feel Whitmarsh’s disappointment that ‘for all this, Lucretius, like his master Epicurus, can still insist on the reality of the gods’. His atheism, like that of the ancient apikoros, is really a denial of divine engagement with the world.

Despite Voltaire’s admiration, Whitmarsh makes it plain that ‘Epicurus’s war on religion was not imagined as an effort to promote secularisation at the state level’. At the same time he reminds us that ‘Stephen Greenblatt has famously argued’ that the recovery of Epicurean doctrine ‘was responsible for European secularism and the Renaissance’.

Yet in another paradox, which Whitmarsh does not go into, it was an earlier renaissance that made possible the very survival of Lucretius’s epic. The oldest manuscript of the poem was written out shortly after AD 800 in the palace school of Charlemagne. We even know the identity of the Irish monk who corrected the errors of transcription: Dungal, an authority on astronomy. What was in it for monks to preserve the reputed arch-atheist of antiquity? Partly, perhaps, that they agreed with Lucretius that the gods of old, as popularly conceived, did not exist.

This line of argument, Whitmarsh says, was employed by the second-century Christian apologist Justin, who saw Socrates’s execution for being an ‘atheist’ as parallel with the Christian denial of the Roman gods. ‘We confess that we are atheists,’ Justin declares, ‘at least as far as these kinds of imagined gods are concerned.’ Whitmarsh is here provoked into reaching for an exclamation mark: ‘Socrates has been reimagined as a Christian martyr!’

But, insofar as the historic Socrates can be recaptured, his ‘playfully subversive humanism’, concludes Whitmarsh approvingly, bore this ultimate message: ‘You make your own principles and you live by them’. I don’t know. That sounds a fine, high ideal, but most people lack the wisdom, time and application to make their own principles from scratch. People happily live as atheists when it is the prevailing culture, just as they happily live without knowing much about ancient Greek culture — because it requires work to learn Greek and for most the prospect seems unappealing.