VATICAN CITY — Encouraging Catholics to participate in the Week of Prayer for Christian Unity, Pope Francis also announced that before the assembly of the Synod of Bishops opens in early October, there will be an ecumenical prayer vigil in St. Peter’s Square. The Week of Prayer for Christian Unity is observed every year Jan. 18-25, and the pope and representatives of other Christian communities in Rome close the week with vespers at the Basilica of St. Paul Outside the Walls. The theme for 2023, “Do good; seek justice,” is taken from Isaiah 1:17. “Let us thank the Lord who guides his people toward full communion with faithfulness and patience, and let us ask the Holy Spirit to enlighten us and sustain us with his gifts,” Pope Francis told people who had joined him Jan. 15 for the recitation of the Angelus in St. Peter’s Square. “The path toward Christian unity and the path of the synodal conversion of the church are linked,” he told the crowd. So, he said, “I would like to take this opportunity to announce that on Saturday, Sept. 30, in St. Peter’s Square, an ecumenical prayer vigil will take place, with which we will entrust to God the work of the 16th ordinary general assembly of the Synod of Bishops.” The assembly’s working sessions are scheduled for Oct. 4-29 and again one year later. Pope Francis also announced that the France-based Taize ecumenical community will lead a special program for young people the weekend of the vigil. “I invite all brothers and sisters of all the Christian denominations to participate in this gathering of the people of God,” the pope said.