Beware the Allure of False Ecumenism: A Response to Pope Leo XIV’s Call for “Full Communion”

The New Pope Delivering His Inaugural Sermon

Unity in Truth, Not Error, Must Guide Christian Communion

By Bp. Joseph (Ancient Church of the West) 

Introduction

Pope Leo XIV’s inaugural sermon on May 18, 2025, as reported by The Stream, has sparked intense discussion among Christians worldwide. By proclaiming Christ as the “rock” of the Church, redefining the Petrine office as a “primus inter pares” (first among equals), and urging “full communion with all Christians,” the new pontiff signals an apparent shift in Roman Catholic ecclesiology. His use of “sister Christian churches” and emphasis on fraternal unity over autocratic primacy suggests an ecumenical openness unprecedented in recent Vatican history. However, Apostolic and Orthodox Christians, anchored in the unchanging truth of the Ancient Faith, must approach this development with discernment. Rome accepting everyone into their communion will not deal with the heresy that they have embraced or promulgated. It will be an ecumenism of the “lowest common denominator,” which is exactly the kind of unity that we should not want - a unity based on accepting their standing and canonical definitions as authoritative.

The Temptation of a Superficial Unity

The appeal of Pope Leo XIV’s vision is undeniable. For Christians weary of division, his call to walk “as a brother” and foster “fraternal communion” strikes a deep chord. Yet, St. John Maximovitch, the revered 20th-century Orthodox hierarch, warned against such compromises: “Unity in truth is one thing, but unity in error, in which each retains his own errors, is the work of the Antichrist.” If this is true, it will present a significant hurdle, as many people will preemptively move into Roman Catholicism not realizing that this is a gimmick and that the reality of Roman innovations, claims and assertions will be extremely difficult to change. Without addressing Rome’s historical innovations - Papal Supremacy, Universal Jurisdiction, the Filioque clause, Immaculate Conception, Purgatory, and other doctrinal deviations - this invitation to “full communion” risks being a superficial gesture, luring Christians desperate for unity into a communion that has not returned to the Orthodox Faith of the Undivided Church.

Scripture calls for vigilance against such compromises. In Ephesians 4:14–15, St. Paul urges believers to avoid being “tossed to and fro by the waves and carried about by every wind of doctrine,” but to “speak the truth in love” and grow into Christ, the head. Rome’s call for communion, while cloaked in love, does not yet demonstrate a willingness to renounce its claims to universal authority or correct its theological errors. The Stream article notes that Leo XIV’s sermon aligns with Vatican documents like The Bishop of Rome (2024), which acknowledges diverse interpretations of Matthew 16:18 but stops short of dismantling the dogma of papal infallibility or supremacy. This suggests a strategic ecumenism that invites others into Rome’s fold without requiring Rome to conform to the Apostolic Tradition preserved by the Ancient Orthodox Church.

Rome’s Innovations Remain Unaddressed

The Stream article highlights Leo XIV’s reliance on patristic exegesis, noting that many Church Fathers, as cited by Archbishop Peter Kenrick in 1870, interpreted the “rock” of Matthew 16:18 as Christ, Peter’s confession, or the apostles collectively, not Peter alone. St. Augustine affirms this view: “For this Church was not built upon Peter, but upon the Rock, that is, Christ Himself” (Sermon 76). Similarly, St. Cyprian of Carthage emphasizes the unity of all bishops: “The episcopate is one, each part of which is held by each one for the whole” (On the Unity of the Church, 5). These teachings align with the Orthodox understanding of a conciliar Church, not a monarchical papacy.

The Seven Ecumenical Councils, the cornerstone of Ancient Orthodox doctrine, further underscore this. The Third Ecumenical Council (Ephesus, 431) condemned any addition to the Nicene Creed, implicitly rejecting later innovations like the Filioque. Canon 7 of Ephesus states: “It is unlawful for any man to bring forward, or to write, or to compose a different Faith as a rival to that established by the holy Fathers assembled with the Holy Ghost in Nicaea.” Rome’s persistence in using the Filioque, despite Orthodox objections, remains a barrier to true unity. Likewise, the Sixth Ecumenical Council (Constantinople III, 680–681) affirmed the equality of all apostolic sees, with no canon elevating Rome above other patriarchates.

Rome’s claim to universal jurisdiction, formalized at Vatican I (1870), contradicts the conciliar spirit of the early Church. As the Stream article notes, Cardinal Joseph Ratzinger (later Pope Benedict XVI) admitted that “Rome must not require more of the East than was formulated and lived during the first millennium.” Yet, Leo XIV’s sermon, while ecumenical in tone, does not explicitly renounce Vatican I’s dogmas of papal infallibility or universal jurisdiction. People are so desperate for unity, recognition and resources that this will be extremely hard to resist for most. So, it will create a very wide movement to join Rome, even as Rome doesn’t change its doctrine back to the original, remove the pope as universal head, or change its stance on its world jurisdiction.

The Danger of Lowest Common Denominator Ecumenism

Pope Leo XIV’s vision, as described in The Stream, emphasizes “unity in faith” but does not clarify whether this faith aligns with the Orthodox consensus of the first millennium or Rome’s post-schism developments. St. John Maximovitch cautioned against such ambiguous ecumenism: “The Church is not a human organization, but the Body of Christ, and its unity must be based on the truth of the Gospel, not on compromises that dilute the Faith” (Homily on the Church). Those in communion with them will rejoice that they are not required to change, but Rome is also not being required to change or repent. This fits the definition of bad ecumenism that St. John Maximovitch actually taught - not that unity in truth is wrong, but unity within multiple errors is the work of the Antichrist.

The Orthodox Churches have consistently rejected such ecumenism. The Council of Constantinople (1872) condemned “ethnophyletism” and any attempt to prioritize national or cultural unity over doctrinal purity. While not directly addressing ecumenism, this council’s spirit applies: unity must not sacrifice truth for expediency. St. Basil the Great echoes this in his call for fidelity to tradition: “We do not innovate, but we preserve what we have received from the Fathers” (Letter 189). Rome’s invitation to “full communion” without renouncing its innovations violates this principle, creating a façade of unity that Orthodox Christians must resist.

A Call for Discernment

The Stream article’s revelation of Leo XIV’s 25-year friendship with a Lutheran pastor and his alignment with Pope Francis’s ecumenical legacy underscores the emotional and relational pull of his vision. Many Christians, desperate for unity, may rush to embrace Roman Catholicism, not realizing that Rome’s innovations remain unaddressed. This is not the unity Christ prayed for in John 17:21, which is rooted in truth: “That they may all be one, just as you, Father, are in me, and I in you.” True unity requires Rome to return to the Orthodox Faith of the undivided Church, renouncing its many post-Schism innovations.

Orthodox Christians must heed St. John Maximovitch’s counsel: “Let us cling to the truth of the Church, which is the pillar and ground of the truth (1 Timothy 3:15), and not be swayed by those who offer unity at the expense of doctrine” (On the Path to Unity). The canons of the Seven Ecumenical Councils, the wisdom of the Fathers, and the unchanging Faith of Orthodoxy provide the roadmap to true communion. As St. Irenaeus of Lyons wrote, “The Church, though dispersed throughout the whole world, preserves the Faith as if occupying but one house” (Against Heresies, 1.10.2). Rome must enter this house, not invite others into a new structure of its own making.

Summary 

Pope Leo XIV’s call for “full communion” is a seductive prospect, but all faithful Apostolic and Orthodox Christians must approach it with caution. Without Rome’s repentance for its doctrinal innovations, such communion risks becoming the “unity in error” St. John Maximovitch warned us against. Let us pray for true unity, grounded in the Apostolic Faith, and resist the temptation to join a communion that does not fully embrace the truth of the Ancient Church. As St. Paul exhorts, “Hold fast to the traditions that you were taught” (2 Thessalonians 2:15), for only in fidelity to the Faith can we achieve the unity Christ desires.

COLLECT 

Almighty and everlasting God, who didst send Thy Son Jesus Christ to be the Way, the Truth, and the Life: Preserve, we beseech Thee, Thy holy Church from all error and false union, and grant that she may ever hold fast the faith once delivered to the saints; that, rejecting the vanity of human pride and the seduction of compromise, she may stand firm in the doctrine of the Apostles, the witness of the Martyrs, and the decrees of the Seven Holy Councils. Give unto Thy people the spirit of discernment, that they may not be led astray by the voice of strangers, but may hearken only unto the voice of the true Shepherd; through the same Jesus Christ our Lord, who liveth and reigneth with Thee and the Holy Ghost, one God, world without end. Amen.