The annual week of prayer for Christian Unity culminates each year on the January 25 feast of the Conversion of St. Paul.
In this Jubilee Year 2025, the week of prayer is particularly powerful, given that this year marks the 1,700th anniversary of the first Christian Ecumenical Council, held in Nicaea, near Constantinople in 325 AD.
Pope Francis and the Ecumenical Patriarch plan to mark the anniversary together in May with a visit to Nicaea (modern-day Iznik, Turkey, about 80 miles southeast of Istanbul).
And, in what is being hailed as a "happy coincidence," the date of Easter this year coincides for East and West.
The Vatican's Dicastery for Promoting Christian Unity published the following explanation and reflection, saying that the 1,700th anniversary "provides a unique opportunity to reflect on and celebrate the common faith of Christians, as expressed in the Creed formulated during this Council; a faith that remains alive and fruitful in our days."
17 centuries
The Week of Prayer for Christian Unity 2025 offers an invitation to draw on this shared heritage and to enter more deeply into the faith that unites all Christians.
The Council of Nicaea
Convoked by the Emperor Constantine, the Council of Nicaea was attended, according to tradition, by 318 Fathers, mostly from the East. The Church, having just emerged from hiding and persecution, was beginning to experience how difficult it was to share the same faith in the different cultural and political contexts of the time. Agreement on the text of the Creed was a matter of defining the essential common foundations on which to build local communities that recognized each other as sister churches, each respecting the diversity of the other. Disagreements had arisen among Christians in the previous decades, which sometimes degenerated into serious conflicts.
These disputes were on matters as diverse as:
the nature of Christ in relation to the Father;
the question of a single date to celebrate Easter and its relationship with the Jewish Passover;
opposition to theological opinions considered heretical;
and how to re-integrate believers who had abandoned the faith during the persecutions in earlier years.
The approved text of the Creed used the first-person plural, “We believe…” This form emphasized the expression of a common belonging. The Creed was divided into three parts dedicated to the three persons of the Trinity, followed by a conclusion condemning affirmations that were considered heretical. The text of this Creed was revised and expanded at the Council of Constantinople in 381AD, where the condemnations were removed. This is the form of the profession of faith that Christian churches today recognize as the Nicene-Constantinopolitan Creed, often referred to simply as the Nicene Creed.
From 325 to 2025
Although the Council of Nicaea decreed how the date of Easter should be calculated, subsequent divergences of interpretation led to the feast frequently being marked on different dates in East and West. Though we are still awaiting the day when we will again have a common celebration of Easter yearly, by happy coincidence, in this anniversary year of 2025, this great feast will be celebrated on the same date by the Eastern and Western churches. The meaning of the saving events which all Christians will celebrate on Easter Sunday, 20 April 2025, has not changed with the passage of 17 centuries.
The Week of Prayer for Christian Unity is an opportunity for Christians to explore afresh this living heritage and re-appropriate it in ways that are in keeping with contemporary cultures ....
