Jewish and Muslim leaders on Monday opened a congress aimed at reconciliation between their faiths by warning that religious strife and terrorism spawned by it are some of the world's gravest threats. "We are standing on the edge of the precipice and looking down," Rabbi Israel Singer, a leader of the World Jewish Congress, said as the four-day meeting got underway in earnest after a ceremonial opening on Sunday night. He likened the congress, organized by a Paris-based peace foundation called Hommes de Parole, and the momentum behind it to the biblical tale of Noah building an arc to survive the world's destruction. Prince Hassan of Jordan, the uncle of King Abdullah, said in a videotaped message sent to the meeting that Muslims and Jews need to work harder to understand each other. Monday's sessions were workshops dedicated to examining how Islam and Judaism can adapt to a rapidly changing world and its effects on institutions like families and morality.