Eastern Orthodox
Commemorates the 318 Fathers of the First Council of Nicaea (325 AD), who defined the full divinity of Christ ("true God from true God, begotten not made, of one being with the Father") against the Arian heresy. This Sunday is a reminder that Orthodox Theology is conciliar — defined by across different churches councils — rather than by any single authority.
It usually falls on or around 5 April 2026. It is especially important in Eastern Orthodox traditions.
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At a glance
- Type
- feast
- Date type
- Moveable (changes with Easter)
- Regions
- Eastern Christianity
- Themes
- Church History, Trinity
- Liturgical colour
- White
Common questions
Sunday of the Fathers of the First Ecumenical Council is observed on 5 April 2026. Moveable feasts shift each year; fixed feasts stay on the same calendar date.
Commemorates the 318 Fathers of the First Council of Nicaea (325 AD), who defined the full divinity of Christ ("true God from true God, begotten not made, of one being with the Father") against the Arian heresy. This Sunday is a reminder that Orthodox Theology is conciliar — defined by across different churches councils — rather than by any single authority.
It is associated with Eastern Orthodox. It falls in the Easter season of the liturgical year.