AD 325 — Nicaea and the Common Pascha
First Ecumenical Council, Nicaea, 325; Eusebius, Life of Constantine III.18-19
Nicaea's calendar decision was about unity: all churches should keep Pascha on the same Sunday. It did not publish a calendar, and it did not canonise Julian arithmetic.
The problem it addressed
Churches were keeping Pascha on different dates — some following the local Jewish reckoning of Passover (the Quartodeciman practice kept it on 14 Nisan whatever the weekday), others always on a Sunday. The scandal was Christians fasting while others feasted.
What was decided
The council determined that Pascha be observed by all on the same Sunday, computed independently of the contemporary Jewish reckoning, following the practice associated with Rome and Alexandria. The imperial letter preserved by Eusebius stresses uniformity above all.
What is often overstated
Popular accounts have Nicaea issuing a precise formula — 'the first Sunday after the first full moon after the vernal equinox'. That formula is the later Alexandrian computus as it developed and was received; the surviving conciliar material is concerned with common observance rather than publishing an algorithm. The distinction matters when someone claims a later reform 'broke a canon of Nicaea'.
Why 1582 could not be a purely civil matter
Because Nicaea's achievement was common observance, any unilateral change to the reckoning raises the question the East pressed in 1583: who has authority to alter something the whole Church agreed together?
Citations on this file
Sources
- Eusebius, Life of Constantine, Book IIIContains the imperial letter on keeping a common Pascha. Nicene and Post-Nicene Fathers translation.https://www.newadvent.org/fathers/25023.htm ↗
- The First Ecumenical Council (Nicaea, 325) — canons and documentsNicene and Post-Nicene Fathers, Series II, Vol. XIV, The Seven Ecumenical Councils.https://www.newadvent.org/fathers/3801.htm ↗
Links are pointers for further reading. The claim is what is sourced, not the website.