Easter Sunday is the most important day in the Christian calendar. It celebrates the resurrection of Jesus Christ from the dead, which, according to the New Testament, happened on the third day after His crucifixion.
Now upon the first day of the week, very early in the morning, they came unto the
sepulchre, bringing the spices which they had prepared, and certain others with them. And they found the stone rolled away from the sepulchre. And they entered in, and found not the body of the Lord
Jesus. Luke 24: 1-3