Christmas does not belong to us.

“Put the Christ back in Christmas,” we’re always told. “Jesus is the Reason for the Season,” they keep saying. Good people speak these things. Unfortunately for such pious folk, Christmas is related to Christianity in the same limited way as Caesar’s wife to history: only by marriage. Christ was never really in Christmas. In fact, when you celebrate Christmas by eating too much, drinking too much, feeling up the boss’ wife at the office party, driving the porcelain bus and/or spending a fortune on presents almost, but not quite, entirely unsuitable for the person to whom you gave them, you come rather closer to the real spirit of Christmas.

In the early days of the Church, Jesus got along fine without a birthday. In any case, birthday parties were worldly, pagan affairs, and Christians did not want to associate the good name of their saviour with any of them. But when Christianity became a faith with claims to universality, the official religion of Constantine’s Empire, this lack of a birthday became something of an embarrassment. Besides, people still expected their twelve days off in December.

Rome’s Saturnalia was a curious mixture of ancient fertility rite and social event. It celebrated the winter solstice, a time when people believed, perhaps, that they needed to make themselves a warm place. It also recalled – for all Romans – a mythical golden age in the distant past when the world was truly merry, a world without war, slavery or hunger.

Romans decorated their doorposts with holly and kissed under the mistletoe. Courts and businesses closed and people greeted one another in the street with shouts of Io Saturnalia! On one day of the twelve, masters waited on their slaves at table while, in the legions, officers served the ranks. A rose was hung from the ceiling in banqueting rooms, and anything said or done sub rosa went no further than the front door. That banqueting could get out of hand is attested to by Seneca, who tells of slaves detailed especially to clean up the spew. The Romans, I should add, had no weekend, so they looked forward to their sanguinary feriae with considerable relish. The festival of Saturnalia was a time, too, for family dinners, for parties, for amours, for socialising, for wishing others well.

And the Romans also did something for which the proprietors of department stores the world over should be eternally grateful. They exchanged gifts. Originally these were small earthenware statuettes known as sigillaria. By the end of the first century, however, Martial provides a list of gifts – with accompanying decorations in verse – that reads for all the world like the John Lewis Christmas catalogue: backscratchers, socks, medicine chests, comforters, woolly slippers, board-games, gold-inlaid dishes, jewellery – among others.

That the commercial aspects of Christmas are Roman in origin should not cause surprise. “No one in Gaul ever does business without the involvement of a Roman citizen,” boasts leading lawyer (and later politician) Cicero in one of his defence speeches, “there is not a denarius jingling in Gaul which has not been recorded in the account books of Roman citizens.” Set into the mosaic floors of a number of homes in Pompeii are the phrases Hello Profit! and Profit is Happiness! Ancient Rome was capitalism without factories.

Christmas is a venerable pagan festival, on a sort of permanent loan from Ancient Rome, and is, perhaps, the very antithesis of Christianity in the lines of its pagan decent. Some of the churches know this, and have left Christmas to the revellers, appalled as much by the Teutonic Christmas tree as by the libidinous connotations of too much wine and too little thought, and, perhaps, by the merry jingle of all those cash registers.

After all, monotheism had to borrow its greatest festival from a bunch of pro-market pagans.