IZNIK, Turkey — On the second day of his inaugural foreign trip, Pope Leo XIV visited the ruins on the shore of Lake Iznik where bishops gathered 1,700 years ago for the First Council of Nicaea, the 325 meeting that produced the creed still recited in many churches today.
The first American pope prayed alongside Ecumenical Patriarch Bartholomew I amid the excavated remains of the basilica where early Christian leaders met to resolve divisive theological disputes. The site, long submerged, was revealed in 2014 when receding waters exposed the church’s apse and dozens of graves.
“We must strongly reject the use of religion for justifying war, violence, or any form of fundamentalism or fanaticism,” Pope Leo said at the lakeside site. “Instead, the paths to follow are those of fraternal encounter, dialogue and cooperation.” On the trip he has pressed for unity among Christian denominations and urged cooperation among religions and communities. Speaking alongside Turkish President Recep Tayyip Erdogan, the pope warned that division and polarization threaten the future of humanity.
Emperor Constantine convened the council to address a doctrinal crisis about Jesus’ relation to God. The most vigorous challenge came from Arius, an Alexandrian priest who argued that Jesus was the highest created being but not equal to God. The assembled bishops rejected Arius’s view and affirmed that Jesus is “of one substance” with the Father, language that underpins the Nicene Creed.
The basilica’s exact location was identified after aerial photographs taken over Lake Iznik were shared with Turkish archaeologist Mustafa Sahin; the ruins had been under about eight feet of water, he told NPR. Locals were already familiar with the stones—when water levels fell swimmers sometimes rested on them—but the more complete footprint of the church became visible as the shoreline receded.
Christian unity endured for centuries until the Great Schism of 1054 split Western (Catholic) and Eastern (Orthodox) Christianity over theological disagreements and competing authority between Rome and Constantinople (modern-day Istanbul). Ahead of the anniversary, Pope Leo issued an apostolic letter calling the creed a “common heritage of Christians,” written while wounds from earlier persecutions were still fresh.
At the historic site, Pope Leo and Patriarch Bartholomew held a joint silent prayer over the exposed ruins. The visit marked a modern effort at reconciliation; the two leaders planned to sign a joint declaration the following day as a further public gesture of unity.