The following is an extract from Tom Holland's latest book, Revolutionary, which explores who Jesus was and why He still matters: 

His coming was foretold by prophecy and his birth heralded by miracles. Only narrowly did he escape a massacre of the innocents. Laying claim to the great mission of his life, he received the blessing of his divine father. Gathering followers drawn from obscurity about him, he scorned the pretensions of monarchs. He condemned those who had offended against his father to a place of wailing and gnashing of teeth; he preached to a war-ravaged world a message of brotherhood and peace.

Many rejected him, but many accepted him as their Lord. In the end, not even death could hold him in its chains. Cheating the tomb, he rose and ascended into heaven. There, seated at the right hand of his father, he reigned in divine majesty. Meanwhile, on earth, his disciples did not forget their risen Saviour. Across the known world, the memory of him was cherished in people's hearts. This, so it was proclaimed in Galatia and in Thessalonia, in Corinth and in Rome, was 'euangelion': 'good news'.

At once a man and a god, mortal and immortal, Augustus Caesar stood at the centre of the fastest growing cult the world had ever seen. The very name awarded him by his countrymen proclaimed his ambivalent status as a human being who had simultaneously partaken of the divine. 'Augustus is what our fathers call anything holy. Augustus is what we call a temple that has been properly consecrated by the hand of the priests.' To worship him as a god was to consecrate one of the great convulsions in world history. His rise to power amid the implosion of Rome's traditional republican form of government was an authentically transformational moment. Ronald Syme, in his classic account of the process, went so far as to describe it as the 'Roman revolution'. Over the course of many decades, a people who had always defined themselves by their contempt for kings were brought to submit to the rule of a general, an imperator, who had been victorious in almost everything he did.

Augustus, as an imperator, an 'emperor', wielded power that was indeed of a revolutionary order. The dominion he governed was vast beyond the dreams of a Pharaoh, and the armed forces he had at his command were on a scale fit to have put Alexander's in the shade. Never before in history had any man enjoyed such fame across such an immense expanse of the world. Within Augustus' own lifetime, no living Roman had ever appeared on a coin minted in Rome; yet by the time of his death, the face of Caesar had become familiar in even the remotest corners of the Empire, wherever money might be handled, and taxes demanded. 'Whose likeness and inscription is this?' Itinerant street preachers in Galilee might ask the question and know the answer.

Yet Augustus, for all the novelty of the order that he founded, did not care to cast himself as a revolutionary. Novae res – "new things" – were regarded by most Romans with deep suspicion.

Augustus himself, who in almost everything save the scale of his ambition was deeply conservative, had far too much respect for tradition to proclaim a year zero. In the wake of the civil wars that had brought him to power, during the session of the Senate that saw the decree passed which defined him as 'Augustus', there were some senators who had pushed for him to be given an alternative name: Romulus. The allusion was to Rome's founder, the man after whom the city was named. There was to be no second founding, however. Augustus had no wish to recalibrate the Romans' understanding of time, which numbered years ab urbe condita: 'from the founding of the city'. There could be only the one Romulus, only the one starting point for the city. The revolution over which Augustus presided was – if a revolution at all – like the turning of a wheel.

The centuries passed. The world did not stay still. Rome's rule over the western half of her empire melted away. Rome itself was sacked. Barbarians planted their kingdoms in what had once been imperial provinces. In one of these, a realm named Northumbria, in a library close to the crumbling fortifications that once, centuries previously, had constituted the frontier of Roman Britain, a scholar by the name of Bede set himself to fashioning a new understanding of time. Rome's fall had not prevented chroniclers from continuing to use the formula ab urbe condita, and Bede, steeped in the learning of his predecessors as he was, employed it readily. Yet it left him dissatisfied. Seven centuries on from the lifetime of Augustus, he could see – infinitely more clearly than the emperor himself had done – that the fulcrum of time was indeed to be identified with a point in his reign. Drawing on calendrical tables compiled some two centuries earlier by a scholar from the Black Sea, Bede began to measure years from this same point: anno Domini, in the year of the Lord.

The Dominus, however, was not Augustus. By Bede's lifetime, the memory of the emperor had become a hazy one, blotted out by the blaze of a very different man. This Lord had not ruled an empire, nor commanded armies, nor had his face minted on coins. Instead, he had been born in the utmost obscurity, lived a life tramping roads and fields, and died a squalid death, nailed to a cross, a convicted criminal. Yet his death had not at all been what it might have seemed. So, at any rate, in Northumbria, it had come to be believed.

There, when a poet saw a cross in his dreams, he could know that it was no 'fracodes gealga' – no 'felon's gallows'. The implement of torture that to the Romans had symbolized the power of the conqueror over the conquered, of the strong over the weak, of the master over the slave, had been transformed, in the imaginings of the Northumbrians, into the very opposite. The paradox of Augustus Caesar, the warlord who had become a god, could not compare with the paradox of Jesus Christ, whose birth in the reign of Augustus as a subject of the Roman state had marked – so Bede believed – the moment on which all of history turned, and who, by his agonizing death, had served to redeem mankind. The cross, that terrible gallows, had become a tree of glory.

At the fair sight, I saw that lively beacon

Changing its clothes and hues; sometimes it was

Bedewed with blood and drenched with flowing gore,

At other times it was bedecked with treasure.

No wonder, then, that the figure of Jesus should have haunted Northumbrian dreams.

Today, a millennium and more since the time of Bede and the author of 'The Dream of the Rood', he lives in the dreams of more people than ever before. Across the planet, over two billion believe that Jesus was indeed the Son of God, Light of Light, very God of very God. 

From 'Revolutionary', the latest book by Tom Holland, out now from SPCK priced £19.99.