The suffering inflicted by Israel on the Palestinian people shows that it has forgotten the Jewish scriptures, Archbishop Emeritus Desmond Tutu said on Saturday.
"They have forgotten their own history. They have forgotten what their own prophets have said about our God," Tutu said in his opening address to the International Russell Tribunal on Palestine.
"We worship a God that is naturally biased in favour of the suffering, the underdog, those who are suffering underfoot... God is always on the side of the oppressed. In the Holy Land, the Palestinian people are the ones suffering."
Tutu said it pained him that a people who went through great suffering could in turn cause others to suffer.
"There is a great deal of preventable suffering being caused by people who themselves suffered so deeply... who have gone through a crucible of suffering.
"Those of us who are Christian have been influenced very greatly by what one might call the Jewish scriptures. The biased God of the past is the biased God of the present... and if God is to be God, watch out," he added.
"This is the anguish that I bear."
The tribunal is an international forum aimed at promoting peace and justice in the Middle East and is meeting until Monday at the District Six Museum.
It met in London and Barcelona last year and a fourth and final meeting will take place in New York later this year. The current session is widely expected to see speakers draw links between the policies of Israel and those of apartheid South Africa.
Panel members include Holocaust survivor Stephane Hessel, author and poet, Alice Walker, Irish Nobel peace laureate Mairead Maguire and former South African Cabinet minister Ronnie Kasrils.
Several Jewish bodies, including the SA Jewish Board of Deputees, have dismissed the tribunal as a kangaroo court.