In a groundbreaking inaugural sermon, Pope Leo XIV redefined the foundation of Christianity by identifying Christ—not Peter—as the “rock” on which the Church is built. He used the phrase “sister Christian churches” to signal a bold ecumenical vision for unity among Catholics, Protestants, and Orthodox believers.
“Love and unity—these are the two dimensions of the mission entrusted to Peter by Jesus,” the Pope declared to over 150,000 Catholics and leaders of other Christian denominations gathered at St. Peter’s Square for his Sunday inaugural Mass.
Quoting Scripture, Leo emphasized, “The Apostle Peter himself tells us that Jesus is the stone rejected by the builders, who has become the cornerstone.” In a significant shift from traditional Catholic interpretation, he argued that since Christ is the rock, Peter’s role is not to dominate but to humbly serve.
“If the rock is Christ,” he explained, “then Peter must shepherd the flock without falling into autocracy or domination.”
He described the papal office as a call to serve and walk alongside believers, highlighting that all baptized Christians are “living stones” (1 Peter 2:5), united in building God’s house in diversity and spiritual harmony.
Drawing from Church History
Leo XIV’s interpretation draws on early Church teaching. He echoed arguments made in 1870 by Archbishop Peter Kenrick, who, during debates over papal infallibility, pointed out that most Church Fathers believed the “rock” in Matthew 16:18 referred to Peter’s confession of faith—or to Christ himself—not to Peter as an individual. Kenrick found that only 17 Church Fathers identified Peter as the rock, while 44 pointed to his confession, and others to Christ or the faithful.
Leo’s approach also reflects the findings of a recent Vatican document, The Bishop of Rome, which emphasized that Christ remains the Church’s true foundation. It warned against projecting modern papal doctrines back onto the New Testament.
The new Pope also quoted Cardinal Joseph Ratzinger (Pope Benedict XVI), who stated that Rome should not require more from Eastern churches “than was lived during the first millennium.” That is, the Pope should act as a unifying figure—not as a supreme ruler.
“I Come to You as a Brother”
Leo’s message was underscored by his statement, “I come to you as a brother,” which the Vatican emphasized in its official text. The phrase signals his intention to reshape the papacy into a model of “first among equals”—a long-standing request from Orthodox, Anglican, and Lutheran communities.
He invoked 1 Peter 5:1, where Peter calls himself a “fellow elder,” and stressed that true authority lies in love, not coercion. “The Church of Rome presides in charity,” he said, referencing Ignatius of Antioch. Ignatius praised the Roman Church but, notably, did not refer to a bishop of Rome—a point scholars cite as evidence that a monarchical papacy did not yet exist.
Historian Hans Küng and Catholic scholar Eamon Duffy both affirm that, for the Church’s first century and a half, there was no singular Roman bishop. Instead, Christian communities in Rome operated through multiple elders meeting in house churches.
Ecumenical Embrace
On Monday, Pope Leo welcomed leaders from other Christian and non-Christian faiths, acknowledging the ecumenical groundwork laid by Pope Francis. “Unity must be unity in faith,” Leo said. “One of my priorities is to seek full and visible communion among all who profess the same faith in the Triune God.”
He praised Pope Francis for promoting ecumenism and interfaith dialogue, calling him “the Pope of Fratelli Tutti,” and urged believers to continue in that spirit.
Use of “Sister Churches” Signals Change
Vatican insiders confirmed that Leo XIV wrote his own sermon, and one described it as “coded language” for an “ecumenical papacy.” Notably, his use of “sister Christian churches” breaks from past terminology. While Vatican II referred to Protestants as “separated brethren” and their churches as “ecclesial communities,” Leo’s wording places all Christian bodies on more equal footing.
In contrast, a 2000 doctrinal statement from Pope John Paul II had emphasized that the Roman Catholic Church is the “mother” of all other churches, and rejected any suggestion of parity.
Yet Pope Leo’s choice of language—and his vision—has already drawn praise. U.S. media highlighted his long friendship with Rev. John Snider, a Lutheran pastor in Minnesota, who said of the Pope: “He knows how to love, and that has not changed.”
