Church leaders from Syria, Russia, the United States and Europe have said that a political solution is the only way to secure peace in Syria.
They are urging "public outcry" against the ongoing civil war that has killed at least 100,000 people and forced two million to flee from their homes.
The comments follow a meeting at the Ecumenical Institute in Geneva, Switzerland with Kofi Annan, the former United Nations general secretary, and Lakhdar Brahimi, UN-Arab League joint representative for Syria.
The meeting was organised by the World Council of Churches to discuss the role of churches in moving Syria towards a peace agreement.
Reverend Dr Olav Fykse Tveit, WCC general secretary, said peace efforts "must not fail now when thousands of people have already died".
He said the international community and all parties to the conflict in Syria had to take responsibility to make peace talks successful and that churches must support the process.
A communiqué issued at the end of the meeting said: "Churches must continue to raise their voice in their congregations, in their societies and with their governments. We must strengthen the public outcry so that those in power will protect the common interest of humanity. Humanitarian assistance is a vital aspect of the churches' mission and solidarity with those suffering."
It added: "We believe there can be no military solution to the crisis in Syria. It is time for the international community to assume its responsibility to end the violence and initiate a political process that brings peace for all the people of Syria."
Mr Annan noted that Syrian churches "are against the use of force and further militarisation".
He expressed support for churches taking the initiative to ask their politicians and parliamentarians to speak out for peace in Syria.
Lakhdar Brahimi also praised the churches' support for peace in Syria and expressed his hope for cooperation from all sides of the conflict towards a political solution.
He said: "We cannot give up on Syrian people because they deserve better than what they are experiencing."