Christian leaders including Pope Francis, Archbishop of Canterbury Justin Welby, Ecumenical Patriarch Bartholomew, and World Council of Churches general secretary, Rev Dr Olav Fykse Tveit, were among hundreds of faith leaders who gathered in Assisi, Italy, this week to join in the Day of Prayer for Peace.

Initiated by Pope John Paul II in 1986, the three day interfaith prayer gathering - this year marking its 30th anniversary - reportedly attracted more than 450 faith leaders and some 12,000 participants.

In the event's closing ceremony on 20th September, Pope Francis quoted Matthew 5:9 - "Blessed are the peacemakers" - and told those gathered that "we thirst for peace". "We desire to witness to peace," he said. "And above all, we need to pray for peace, because peace is God’s gift, and it lies with us to plead for it, embrace it, and build it every day with God’s help.”

Speaking at the same ceremony, Archbishop Welby, said: "We need to be reminded daily of our poverty in spirit, to thirst for the riches of God’s mercy. We are all to drink daily of that mercy in order to overcome our sin and anger, and to bear mercy to others.”

Earlier, Rev Dr Tveit, speaking at a panel discussion entitled 'Terrorism - A Denial of God', said no-one can claim the name of God "to use terror or violence". "Terror is a blasphemy against God our creator, who created all of us equally in the image of God. Terror is sin against other human beings, against the sanctity of life, and therefore against God."

Noting that religions themselves have been part of the problem, he said faith leaders "should be critical and self-critical". "There must be space for self-critique and repentance, for constructive imagination that opens doors for healing and reconciliation and the life-giving presence of God who renews all life".