The latest Apostolic Letter of Leo XIV, In unitate fidei, represents a document destined to leave a significant mark on the journey of dialogue between the Catholic Church and the Orthodox Churches. Not only because of its strong reaffirmation of the heart of our common faith—the Christological proclamation of the Council of Nicaea—but above all for a gesture without precedent in the magisterium of the Latin Church: the explicit recognition that the expression "and from the Son (Filioque)" does not belong to the original text of the Niceno-Constantinopolitan Creed, but was later inserted into the Latin Creed by Pope Benedict VIII in 1014.
This clarification has an epochal theological, historical, and ecclesial value. For over a millennium, the Filioque has been one of the most delicate issues in the division between East and West. It is not a secondary detail, but rather an identity marker of the faith as professed in the two great Christian traditions. The fact that a Latin pontiff officially affirms not only the later historical origin of the Filioque, but also that it "is the object of Orthodox–Catholic dialogue," represents a true opening, a recognition of the dignity of the other theological tradition, and a meaningful change of podsture.
For centuries—often implicitly—it has been taken for granted that Latin theology constituted a sort of "unilateral norm" of Trinitarian understanding. Today, with sober and respectful language, Leo XIV acknowledges that the formulations of the Creed have been historically plural and that the insertion of the Filioque belongs to a specific context—the Western first millennium—and not to the universal Tradition of the early Ecumenical Councils. It is, therefore, both a restoration of historical truth and a gesture of fraternity toward the Christian East.
But there is more. Leo XIV does not limit himself to a doctrinal act of reconciliation. He articulates a style, a vision, a method: "This does not mean an ecumenism of return to the state prior to division, nor a mutual acknowledgement of the current status quo of ecclesial diversity, but rather an ecumenism oriented toward the future, of reconciliation along the path of dialogue, of exchange of our gifts and spiritual patrimonies." Here emerges a dynamic concept of unity, neither nostalgic nor relativistic: the goal is not to go backward, nor to settle for a "federation of differences," but to move toward a new unity, the fruit of mutual purification, listening, and spiritual synergy.
And it is precisely on the level of these "concrete spiritual gifts" that another step enters into play for visible unity: a single date for Easter. It is explicitly among the desires expressed by Leo XIV and among the profound hopes of many Christians throughout the world that the Catholic Church may finally take the step of adhering to the common practice of the Orthodox world—namely the celebration of Easter according to the calculation established by the Council of Nicaea itself: Easter on the first Sunday after the first astronomical full moon of spring observed in Jerusalem, calculated according to the Julian calendar.
The Eastern Catholic Churches already follow this practice: they celebrate Easter according to the Julian calendar and Christmas according to the Gregorian calendar, acting as a concrete bridge between the two great ecclesial sensibilities. This model, already in operation, represents a valuable example of liturgical inculturation and harmonization of traditions.
Adopting a common Easter date would not be a mere technical calendar operation, but a prophetic sign of communion. It would mean, with humility and courage, accepting a gift from the East: because the Nicene–Julian paschal calculation is not a simple convention, but a theological heritage of the undivided Church of the first millennium.
In this sense, we can say that Leo XIV has prepared the ground. He has opened a space of shared and reconciling truth: acknowledging the historicity of the Filioque—without denying Latin theology—means rejecting the temptation of uniformity and choosing the path of the symphony of Traditions.
It now falls to the Catholic community—pastors, theologians, faithful—to take the next step: to transform the theological climate into concrete liturgical gestures. A single Easter celebrated on the same day, once a year, one proclamation: "Christ is risen!" This would be the sign that unity is not an abstract concept, but a lived reality.
The upcoming extraordinary consistory and the meetings to be held in Nicaea on the occasion of the 1700th anniversary can become—as the Apostolic Letter hopes—a laboratory of unity, a place for courageous decisions. The Christian East does not await gestures of supremacy, but gestures of fraternity. And the Catholic West, today more than ever, has the possibility of showing spiritual maturity and love for the undivided Church.
The future of ecumenism passes through very concrete choices. Among them, perhaps none more eloquent than unity in the date of Easter: because celebrating together the Lord's resurrection means truly recognizing ourselves as one Body, risen with Christ, in history and in time.
Marco Baratto
