By Robert Pigott
BBC religious affairs correspondent, Jerusalem
The rift in the Anglican Communion - superficially over homosexuality - has been widening steadily ever since the ordination by its American wing of the openly-gay bishop Gene Robinson in 2003.
Gene Robinson is the Episcopalians' first openly gay bishop
But the meeting in Jerusalem of Bishop Robinson's fiercest critics seems to promise a dramatic step up in the crisis.
Three hundred traditionalist bishops and archbishops - who believe that the Bible outlaws active homosexuality - are staging what is in effect a rival meeting to the Lambeth Conference, the 10-yearly gathering of Anglican bishops from all over the world, that plays a vital part in knitting together this disparate and unwieldy Communion.
Many of the traditionalists at the Global Anglican Future Conference (Gafcon) in Jerusalem - including English bishops - plan to boycott Lambeth.
They are also drawing up what amounts to a blueprint for an alternative Anglican Communion.
The meeting's location in Jerusalem is highly symbolic.
The traditionalists here are demanding that the Communion as a whole - including the Americans - go back to the stricter reading of the Bible they say would have applied in the early history of the Church, born here 2,000 years ago.
The Archbishop of Uganda, Henry Orombi, - who is boycotting the Lambeth Conference - said his wish was to emulate the first Christians.
"I want that we go back to the first love that the early Church had in Jerusalem, that inspired them to mission, that allowed them to make sacrifices, that we go back to believing the word of God to be the word of God, as it is in the Bible."
Gafcon traditionalists, such as Archbishop Orombi, believe liberals are reinterpreting the Bible to suit contemporary morals.
A booklet issued by the conference's organisers puts it this way: "We want unity, but not at the cost of re-writing the Bible to accommodate the latest cultural trend."
On Monday all 303 bishops and archbishops will put on their colourful robes and walk up the Mount of Olives.
The message to the rest of the Anglican world will be that a new, more conservative Communion would be ready to give up its links with Canterbury if that is what it takes to return to what it sees as the original teaching of the Church.
Any new Communion would be likely to have profound implications for Anglican churches all over the world, because it would provide a choice; a potential home for traditionalists disillusioned with liberal policies towards homosexuality in their own churches.
But some of Gafcon's most senior figures say they see it less as an alternative Communion than a powerful voice for traditionalism within the camp, and perhaps a lobby to dilute the power of the Archbishop of Canterbury to lead the world's Anglicans.
The ordination of women has also caused divisions within the Church
The Archbishop of Sydney, Peter Jensen said: "The Archbishop of Canterbury occupies a role of great esteem and honour amongst us. I don't think it will change. There will be others as well who are active within the Communion who will also exercise leadership.
"So this is not an attack on Lambeth, but a recognition of the reality of the way in which this family has ceased to be a nuclear family but has become an extended family."
The traditionalists in this extended family may decide that their influence is best used to press for a clearer statement of agreed beliefs about sexuality, and for more discipline to enforce them.
Many of those who are angry about liberal policies on sexuality would refuse to join action as radical as splitting to form a new Communion.
The presiding Bishop of Jerusalem and the Middle East, Mouneer Anis, is an example.
He declined to attend Gafcon, and has urged organisers "not to make binding decisions which may result in dividing Anglicans in the global south and elsewhere".
Another doubt may haunt this week's meeting in Jerusalem: that a formal split now would simply expose the divisions that undoubtedly exist even within the Gafcon organisation.
One commentator in Jerusalem, editor of the Church Times Paul Handley, says a united front over homosexuality could easily break down in the face of other differences, such as the ordination of women bishops.
"The easiest way of uniting people is to have an enemy, and if you then split away from that enemy, then you've got no reason to be together until you start looking at each other, and then you start looking for another enemy within your ranks┐ and that's the history of Church schism."
However, the traditionalist lobby at work in Jerusalem cannot be ignored.
The centre of gravity in the Communion has shifted steadily south as Anglican churches in developing countries have grown, and those in the developed world have shrunk.
Even if they retain a sentimental attachment to the Communion, African and Asian church leaders are not inclined to adopt what they see as changes in theology imposed by the former colonial churches that first brought them the Bible.