Giles Fraser travels to Bethlehem to reveal the true origin of Christmas - and discovers it was invented over 300 years after Christ's birth.

Christmas was unknown to the early church. In fact the festival of Christ's birth wasn't invented until 312AD, and not by a peaceful disciple, but by a military leader, the Roman Emperor Constantine.

Following his battlefield conversion, Constantine established Christianity as the official religion of Rome, and he decided that Christ's birth should become a major focus of the Christian year. At the same time he radically reinvented Christianity for his own - military - ends.

Giles Fraser visits Jerusalem and Bethlehem, and sees the two major shrines founded by Constantine, which celebrate Christ's birth and death. He argues that by focusing on the birth of Christ, and on his death, Constantine pushed the radical Christ of the early church to the margins of Christianity and replaced him with an infinitely more accommodating religion of the baby and the cross, so the bit in the middle - the radical, questioning life of Christ - was skimmed over.

By marginalising Christ's teachings about poverty, humility, and above all peace, Constantine was able to take a religion founded in pacifism and use it for his military machine in pursuit of a 'just war' - something political leaders have been doing ever since.

Giles Fraser argues that we should look beyond the trappings of Christmas and return to the true, radical teachings of Christ.

Giles Fraser is the former Canon Chancellor of St Paul's Cathedral. An outspoken, enthusiastic and challenging broadcaster, he is a familiar voice on Radio 4's Thought for the Day, and writes a regular column for the Guardian.

Producer: Jane Greenwood

A Loftus Audio production for BBC Radio 4.