Less than three weeks since the leader of Egypt’s Christians narrowly escaped an Islamist attack that killed scores of Palm Sunday worshipers, Pope Francis stood in his presence, committing himself to continue on a path toward the full communion of their Churches.

That path, he said, as he has said before, includes an “ecumenism of blood.”

Francis addressed Pope Tawadros II, patriarch of the Coptic Orthodox Church, on Friday, his first day in Egypt. The meeting took place at St. Mark’s Cathedral in Cairo’s Abbassiya district. The two popes took part in ecumenical prayers at the adjacent Church of St. Peter, the site of a deadly blast in December that left at least 23 people dead, according to CNN.

“The deepening progress of our ecumenical journey is also sustained, in [a] mysterious and quite relevant way, by a genuine ecumenism of blood,” said Francis, wearing a Coptic cross in place of his simple pectoral cross. Whoever believes in Christ “overcomes the world,” he said, “by living a new life in our common baptism, a life of love always and for all, even at the cost of the sacrifice of one’s life. How many martyrs in this land, from the first centuries of Christianity, have lived their faith heroically to the end, shedding their blood rather than denying the Lord and yielding to the enticements of evil, or merely to the temptation of repaying evil with evil! … Even in recent days, tragically, the innocent blood of defenseless Christians was cruelly shed: their innocent blood unites us. Most dear brother, just as the heavenly Jerusalem is one, so too is our martyrology; your sufferings are also our sufferings. Strengthened by this witness, let us strive to oppose violence by preaching and sowing goodness, fostering concord and preserving unity, praying that all these sacrifices may open the way to a future of full communion between us and of peace for all.”

On Palm Sunday, two suicide bombings took the lives of 45 worshipers at churches in Tanta and Alexandria, the latter at St. Mark’s Church, where Tawadros had celebrated Liturgy just hours earlier.

The Coptic Orthodox Church, tracing its roots to St. Mark’s establishment of the Church in Alexandria, is one of the Oriental Orthodox Church that fell out of communion in the 5th century over a dispute concerning the nature of Christ.

Francis and Tawadros signed a joint declaration reiterating the fraternity between their churches.

“Let us intensify our unceasing prayer for all Christians in Egypt and throughout the whole world, and especially in the Middle East,” the declaration states.

Francis also recalled the Common Declaration signed by Pope Paul VI and Pope Shenouda in 1973.

“After ‘centuries of difficult history’ marked by increasing ‘theological differences, nourished and widened by non-theological factors,’ and growing mistrust, we were able that day, with God’s help, to acknowledge together that Christ is ‘perfect God with respect to his divinity and perfect man with respect to his humanity,'” Francis said. “Yet equally important and timely are the words that immediately precede this statement, in which we acknowledge Jesus Christ as ‘our Lord and God and Savior and King.’ With these words, the See of Mark and the See of Peter proclaimed the lordship of Jesus: together we confessed that we belong to Jesus and that he is our all.”

A theological dialogue between the Catholic Church and the Coptic Orthodox Church continues to hammer out differences. It met in Rome this year and in Alexandria last year.

“Not only is there an ecumenism of gestures, words and commitment, but an already effective communion that grows daily in living relation with the Lord Jesus, is rooted in the faith we profess and is truly grounded on our baptism and our being made a ‘new creation’ in him,” Francis told Tawadros.

The Roman pope also suggested that members of the two churches demonstrate unity by doing charitable works together.