The World Council of Churches held an ecumenical celebration in Geneva over the weekend to mark its 75th anniversary.
Hundreds gathered from around the world in the city's Saint Pierre Cathedral for a commemorative service.
The World Council of Churches (WCC) was formed in 1948, when Europe was still recovering from the destruction of World War Two.
The very first Assembly of the WCC met in Amsterdam from 22 August to 4 September 1948, and was attended by 351 delegates from 147 churches.
Working for peace and reconciliation was one of the WCC's principal aims when it was founded.
Addressing the service on Sunday, the moderator of the WCC's central committee, Bishop Heinrich Bedford-Strohm, recalled the founding vision of the ecumenical organisation.
"People came together in Amsterdam in 1948 with a clear purpose of leading the churches of the world together and making them an instrument of peace," he said.
"They clearly declared that war is against the will of God and that our task as Christians is exactly to overcome nationalism and other forms of division between peoples, which had just resulted in this terrible world war with so many million victims.
"Reconciliation was from the very beginning of its existence, part of the very DNA of the WCC."
Reflecting on whether member churches were living up to the legacy of Amsterdam and acting as instruments of peace in conflict zones, he said, "I wish the answer was a clear 'yes.' But it is not. Too often, we still put our national or political loyalties before our loyalty to Jesus Christ, and sometimes we don't even notice it.
"That is why we have to listen to the biblical witness about Christ again and again."
The anniversary service fell during the meeting of the WCC's central committee in Geneva, where the organisation's headquarters are based.
An anniversary cake was cut by former WCC deputy general secretary, Georges Lemopoulos, and Maria Yaziji, of the Greek Orthodox Patriarchate of Antioch and All the East, the youngest member of the current central committee.
In a video message to the celebration, the Coptic Orthodox Archbishop of London, Archbishop Angaelos, noted that the WCC faces many challenges "that can be difficult sometimes".
"But the rewards, the blessings, the light that we shine into the world, the salt that we can be of the earth, and the example, serving others as our Lord, serve the whole of humankind—all of these things make the World Council of Churches, a wonderful platform for us to come together," he said.
