Every pilgrim will want to venerate the place where Jesus is said to have been crucified and entombed. The trouble is that the church, rebuilt by the Crusaders 900 years ago on Byzantine ruins, has only one door.
That is adequate in a normal year, when there are about 700,000 visitors and the church is open eight hours a day. But with five times that number, it is a prescription for disaster. At Easter in 1840, 500 pilgrims died in a stampede when the church caught fire during the Greek holy fire ceremony.
"You can't open a cinema without at least two doors," Uri Mor, director of the Christian communities department in the Religious Affairs Ministry, said. So the Israelis are proposing to open a second door, enabling pilgrims to go in one end and out the other.
The three denominations sharing control under a fragile "status quo" dating back to the 1850s - the Greek Orthodox, the Armenians and the Catholics - have agreed in principle, so long as it is defined as an "emergency" door. They can argue about it again once the emergency of 2000 is over. But that is only the first step.
Mr Mor, a mild Jewish bureaucrat who grew up in Nazareth, is negotiating a way through the labyrinth. Where exactly will the door be cut? Who will hold the key? Will it be an exit, or an entrance? Above all, will any of the churches gain or lose an inch of holy stonework? Will it give a rival a precedent?
So far, they have agreed that it will be an exit only. Since Saladin conquered the holy land from the Crusaders, the key has been kept by two Muslim families. The churches trust them, but not each other. That will remain the only entrance.
The logical route is down a corridor, now blocked, that existed during Crusader times. The arches are still visible. But to reach an exit there, you would have to go through an iron door and a small room. The Greeks hold the key to the iron door. The Armenians fear that pushing a corridor that way would give the Greeks more rights. They would have the key to the new exit.
So the Armenians are proposing an alternative route. The Israelis checked, and discovered it would come out in the Al Hanka mosque, which abuts the Christian shrine. The last thing the Israelis want is to bring in the Jerusalem Muslims, which would mean Yasser Arafat's Palestinian Authority.
Then there is the question of where the other exit will emerge. That will require the consent of two lesser churches, the Copts and the Ethiopians, who have been locked in conflict for the past 20 years over a tiny monastery, built on the roof of the Holy Sepulchre.
The Israelis are hoping for an answer early in the new year, but Mr Mor is not betting on it. The precedents are discouraging. When the cupola soaring above the Holy Sepulchre was restored earlier this decade, he says, "it took them 30 years to decide what the colour should be". He added: "We work in minutes; they have their own system of time."
The churches have been arguing for 27 years over who should repair the four arches of the rotunda over the tomb of Jesus. The Greeks, the Armenians, the Copts and the Syrian Orthodox all staked a claim. "If you repair," Mr Mor explained, "you are the owner."
In the end, the Religious Affairs Ministry is doing the job, at a cost of $250,000 to the Israeli taxpayer. The rival patriarchs have signed the plans, but the Syrians are trying to seize another two inches nearer the tomb. Mr Mor goes there every day to make sure nothing is a fraction out of place.