From Eostre, a Saxon goddess celebrated at the spring equinox. In Christianity Easter is the annual festival commemorating the resurrection of Christ, observed on a day related to the Passover full moon but calculated differently in eastern and western churches.

In the Bible the Passover (Hebr. pesaḥ, Grk. and late Lat. pascha, hence the adjective “paschal”) is part of the divine order, Israel's annual commemoration of deliverance (Exod. 12; Deut. 16; Heb. 11.28). For New Testament writers, Christ is the Christian Passover victim (1 Cor. 5.7), and the Gospel presentation has often a Passover background; see Luke 2.41 and the synoptic passion narrative (Matt. 26.2 par.), according to which the Last Supper appears to be a Passover. In John there are three Passovers: John 2.13, which is associated with the cleansing of the Temple; John 6, where the feeding of the five thousand has paschal and eucharistic echoes (the synoptic accounts may also have a paschal origin); John 11–13; 18.28, 39; and 19.23–37, where Jesus dies on the cross according to this Gospel's chronology at the time when the Passover lambs were being slaughtered in preparation (19.31) for the feast. Christ is thus the eternal paschal lamb; see John 19.36 (cf. Exod. 12.46) and John 1.29, 36; see Lamb of God.

Easter is therefore the Christian Passover, celebrated for some time on the night of fourteenth of the Jewish month Nisan (Passover night) on whatever day of the week that date fell. This custom continued long in Asia Minor (as in Celtic Britain), with those maintaining it being called Quartodecimans (“fourteeners”), but in Rome Easter was observed on a Sunday from a date that is difficult to determine but earlier than 154 CE, when Polycarp of Smyrna, a Quartodeciman, on a visit discussed the different observances with Anicetus, head of the Roman church.

The transfer of Easter to the first day of the week was no doubt because Sunday had become the Christian weekly day for worship. That this was owing to the Lord's resurrection on Sunday is not provable but suggested strongly by the New Testament evidence and the absence of any convincing alternative theory. The first day of the week marks the discovery of the empty tomb (Matt. 28.1 par.), while on the same evening the meal recalls the Last Supper (Luke 24.30). See also John 20.1, 19 and 26, the last being the Sunday a week later, and Acts 20.7, which again suggests the custom of a Sunday evening Eucharist. Paul call the Eucharist the Lord's supper (1 Cor. 11.20); the word for “Lord's” recurs in the New Testament only in Revelation 1.10 in “the Lord's day.” It was probably “the Lord's” because it was the day for the Lord's supper or Eucharist, at which the Lord had been physically present before his crucifixion, and especially on the day of his resurrection and subsequent days (to which Acts 1.4 and 10.41 probably refer), and invisibly ever since, anticipating his final coming.

A. R. C. Leaney