It is a 90-mile route defined by the journey of Mary and Joseph 2,000 years ago, although Matthew, Mark, Luke and John are unhelpful about the exact route, and the Bible does not mention the traditional nativity scene donkey.

Any direct route that foot passengers would have taken in the era of Caesar Augustus, retraced today, inevitably draws you into the tangled skein of modern Middle East politics, through Israel and the occupied West Bank, past Hamas strongholds and extremist Jewish settlements lying Islamic cheek by Zionist jowl.

But first you slam into a checkpoint. The first, that is, of 15 Israeli military roadblocks and mobile checkpoints that now control passage along the roads south from Nazareth.

It is a huge yellow gate at Jalame, close to the old, invisible, green line that separated Israel and the West Bank before Ariel Sharon’s “separation” strategy gave birth to the million-pound-a-mile razor wire and concrete barrier that Israel has built around — and deep into — the West Bank. The gate at Jalame — the northern edge of this “security fence” (Israeli ) or “apartheid wall” (Palestinian) is flanked by a watchtower and razor wire. But it swings open unusually quickly upon the production of foreign passports and press cards and the car slips through.

Inside is Jenin, stronghold of Islamist militant groups whose suicide bombers and gunmen are the reason Israel cites for the gates and guards. Posters here glorify Hamas fighters and Iraqi soldiers in the Arab armies that sought to crush the nascent State of Israel in the 1948 war. On the other side of Jenin lies another Israeli checkpoint, halting a trail of cars with the distinctive green numberplates that identify them as Palestinian, not Israeli, vehicles. Then another flying checkpoint, then another, and another again as the road winds past cucumber fields and orange groves past the recently evacuated Jewish settlement of Khomesh until Shavei Shomron, still occupied by settlers.

This is a controversial stretch of tarmac — in effect an Israeli-only road in the heart of the occupied Palestinian Territories along which, local farmers and Israeli soldiers confirm, only Palestinian doctors and humanitarian vehicles can pass. However, a British newspaper has no problem. Just as Joseph and Mary, as Jews, would have been allowed to pass.

But local Palestinians are angry, complaining that the restrictions prevent them from visiting relatives just a mile away. Umm Hani pointed to the Jewish settlement looking down on her home in the forbidden road and said: “I live here but they forbid us to bring our car to our own house. It’s like a prison.”

Israel insists that it has lifted many roadblocks, but must protect its West Bank settlements. “The construction of the fence has allowed us to make a dramatic and consistent reduction in checkpoints over the past few months,” said Mark Regev, an Israeli Foreign Ministry spokesman. “But you have got to remember that you have Jewish communities on the other side of the fence.”

Until agreement on President Bush’s road map, he said, Israel could not leave its remaining outposts “like ducks in a shooting gallery”.

South of Jenin the road winds through olive groves and then reaches Nablus and Ramallah, Palestinian cities entirely sealed in by Israeli checkpoints that have mutated in recent months from jerry-built constructions to vast steel and concrete enclosures. South again and Jerusalem appears in the distance, entry to the city prohibited to Palestinian vehicles. And finally Bethlehem. Here politics and religion collide once more, with Palestinians emitting howls of outrage at the 30ft-high Israeli wall that was completed just before Christmas. Acutely aware of the sensitivity of Bethlehem to Christians, Israel has promised that the crossing will open 24 hours a day for Christmas. “Pilgrims will not need permits,” Mr Sharon’s government promised.

Lieutenant Colonel Aviv Feigel, the Israeli army’s district co-ordinator, said: “We are taking a calculated risk by easing steps and that is because we are well aware of the importance of Bethlehem.”

Inside Bethlehem, goodwill is hard to find. Since the outbreak of the intifada in September 2000 Christmas celebrations have been dismal, Dr Victor Batarseh, the town’s mayor, says, pointing to a dwindling Christian population and the rising wall. “Now Bethlehem has become a big prison for its citizens. We are remembered one day a year. On Christmas Eve all the world speaks of Bethlehem but they give nothing to us. Nothing.”

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