Easter
Traditionally, Easter commemorates the resurrection of Jesus Christ. In the New Testament, several texts make up the theology and significance of Easter. In the Gospels, Easter closely aligns with the passion narrative (Matthew 26-27, Mark 14-15, and Luke 22-23).
The text that opens Easter events describes Jesus' triumphal entry into Jerusalem (Matthew 21:1-11). Among other things, The event marks the beginning of the final week leading up to Jesus' crucifixion and resurrection.
The entrance into Jerusalem is followed by the Last Supper (Matthew 26:17-30, Mark 14:12-26, Luke 22:7-39, and John 13:1-17:26) where Jesus inaugurates a new covenant between God and humanity (cf. Jeremiah 31:31-34, Ezekiel 36:26-27). This is done by a symbolic act of breaking bread and drinking wine with the disciples which should be later repeated in remembrance of his sacrifice "until he comes" again (1 Corinthians 11:23-26).
The Last Supper also refers to Passover, or Pesach, which is a significant event marking the liberation of the Israelites from Egyptian slavery. The term Passover derives from the Hebrew verb פָּסַח [pāsaḥ], which means "skip" or "spare," referring to how those who followed God's instructions were spared from the destruction that befell the Egyptians. The Israelites sacrificed a lamb and marked their doorposts with its blood, signifying their obedience to God.
After the Last Supper, Jesus and his disciples sang a hymn and departed for the Mount of Olives, where the events leading to Jesus' arrest and crucifixion begin to unfold.
On Friday, the biblical narrative recounts the crucifixion of Jesus Christ (Matthew 27:32-56, Mark 15:21-41, Luke 23:32-49, John 19:17–30). The passage describes Jesus being led to Golgotha, the place of crucifixion, where he is nailed to the cross. Despite the pain and humiliation, Jesus endures the crucifixion, ultimately actively - of his own volition - giving up his spirit and dying.
As was prophecized three times by Jesus (#1: Matthew 16:21, Mark 8:31, Luke 9:22; #2 Matthew 17:22-23, Mark 9:30-31, Luke 9:43-45; #3 Matthew 20:17-19, Mark 10:32-34, Luke 18:31-33) that this is not the end of the story. Jesus is miraculously resurrected (Matthew 28:1-10, Mark 16:1-8, Luke 24:1-12, John 20:1-18). The event of resurrection marks the vindication from the Father and the fulfillment of Jesus' promise to rise from the dead.
The whole story concludes with Jesus being taken up into heaven (Acts 1:6-11). Jesus promises the coming of the Holy Spirit and commissions his disciples to be his witnesses throughout the world. The passage concludes with the assurance that Jesus will one day return in the same way as he ascended into heaven.
It was The First Council of Nicaea in 325 AD that established a standardized date for celebrating Easter, aiming to create uniformity among Christian communities. The council decided that Easter should be observed on the first Sunday following the first full moon after the vernal equinox.