The Churches Mark 1,700 Years since Nicaea

The bishops gathered at Nicaea in 325 confessed the Son of God as “of one substance” with the Father (Creed of Nicaea (325)); see the First Council of Nicaea.

For the 1,700th anniversary, in 2025, the World Council of Churches made a world conference on Faith and Order, its sixth, the centrepiece of its commemoration (World Council of Churches, Sixth World Conference on Faith and Order (2025) event page). It met from 24 to 28 October at the monastery of St Bishoy at Wadi El Natrun in Egypt, on the theme “Where now for visible unity?” (World Council of Churches, Sixth World Conference on Faith and Order (2025) event page). Its message thanks the Coptic Orthodox Church for its hospitality and says that the Nicene creed reminds the churches of a shared gift and call to full, visible unity (World Council of Churches, Sixth World Conference on Faith and Order (2025) Message).

On 23 November Leo XIV issued the apostolic letter In unitate fidei as he prepared to travel to Türkiye (Leo XIV, In unitate fidei 1). It calls the creed, with baptism, the foundation of ecumenical dialogue, and describes an ecumenism that neither returns to the state before the divisions nor accepts the present one, but looks to the future (Leo XIV, In unitate fidei 12). It quotes the creed’s article on the Holy Spirit as proceeding “from the Father”, and notes that the words “and the Son” were inserted into the Latin creed in 1014 and remain a subject of Orthodox–Catholic dialogue (Leo XIV, In unitate fidei 8 and note 10).

On 28 November a prayer service was held at İznik, the ancient Nicaea, near the excavated remains of the basilica of St Neophytos (Leo XIV, Address at İznik (28 November 2025) programme of the journey, 28–29 November). Leo, the Ecumenical Patriarch Bartholomew I, heads of other churches and representatives of the Christian world communions took part (Leo XIV, Address at İznik (28 November 2025) booklet for the service, pp. 3, 7–8) (Leo XIV, Address at İznik (28 November 2025)). Leo said that faith in Christ “consubstantial with the Father” is a bond already uniting all Christians, and thanked Bartholomew for deciding to commemorate the council in the place where it was held (Leo XIV, Address at İznik (28 November 2025)). The booklet for the service has Bartholomew introduce the profession of faith and all say it together, with the Spirit “who proceeds from the Father” (Leo XIV, Address at İznik (28 November 2025) booklet for the service, pp. 3, 7–8).

The next day, at the Phanar in Constantinople, pope and patriarch signed a joint declaration (Joint Declaration of Leo XIV and Bartholomew I (2025) bulletin and paragraphs 1–2). It names the faith expressed in the creed of Nicaea as what binds Christians together, while acknowledging obstacles that prevent the restoration of full communion among them (Joint Declaration of Leo XIV and Bartholomew I (2025) bulletin and paragraphs 1–2). It notes that in 2025 all Christians kept Easter on the same day and states a shared desire to go on seeking a way to do so every year (Joint Declaration of Leo XIV and Bartholomew I (2025) paragraph 3). It recalls the declaration of 1965 that set aside the excommunications of 1054 (see Rome and Constantinople Lift the Anathemas of 1054) and supports the official theological dialogue between the two churches (Joint Declaration of Leo XIV and Bartholomew I (2025) paragraphs 4–5).