During the time of the 5th Crusade, while his own countrymen were going to the Middle East for war, Francis of Assisi rather went with the message of peace and approached Sultan Malik al-Kamil of Egypt for a peaceful dialogue.
At the time many of Malik al-Kamil’s court were Coptic Christians, so he was educated on Christianity and accepted the Monk. The Sultan listened to his message, even allowing him also to preach the Gospel. Francis is recorded to have said “he had been sent beyond the sea by Almighty God to show him and his people the Path to their Salvation and to tell them of the Gospel whch is truth” (His Biographer recorded the conversation)
At the time the Muslims and Copts were defending their lands from the Crusaders in Egypt claiming the same Faith as this man and whose mission had been sent by the same Pope in Rome.
This shows how three groups: Muslim, Orthodox and Catholic can sit in a room peacefully whilst violence rages around them. Many say religion causes wars but when men who are pious but have strong religious convictions can listen in peace when those of the same claim kill it shows the ‘proof’ of this is not as clear many say.