“The festival that early Christians celebrated was called in Greek Πάσχα (Pascha), a transliteration of the Aramaic word פסחא, cognate to Hebrew פֶּסַח (Pesach). The word originally designated the Passover feast of Exodus 12. Paul writes from Ephesus that, ‘Christ our Pascha (Passover) has been sacrificed for us'”*.
Passover (Pascha) is a metaphor, a symbol that God will rescue His people from death; i.e. the death angel will pass over your house if he sees the blood of the lamb**. As stated in writings of John the disciple, when John the Baptist first saw the Messiah, he declared, “Behold! The Lamb of God who takes away the sin of the world!” John 1:29 Hence the cross fulfilled the Jewish sanctuary, in its daily, weekly, festal, and yearly sacrifices and rites. Why? Because the fulfillment of the symbols had come to be sacrificed, once and for all time, for the sins of the people.
Easter (while its name is a borrowed pagan holiday of spring) is essentially the celebration of the fulfillment of the symbols of the covenant made with Israel, for the Messiah died on: Passover, Sabbath, high Sabbath week, and the day of atonement, all at one time! Nearly every symbol from Moses through Solomon met its fulfillment in God giving His own Son’s life. There is no longer any debt owed for our failures of conscience. In this one act, God was now able to rescue His wayward children from our penchant for self-destruction.
*Wiki definition of Pascha. For More education on Easter: http://en.wikipedia.org/wiki/Easter
**The plagues of Egypt culminated in the death of the first born, the only way to protect themselves from the plague was to cover the doorpost of the home with the blood of a sacrificed innocent lamb. In this way the death angel would see the blood and not kill the first born of that family and of anyone hiding within it.
Pic: Shayne Mason Vincent, http://www.baringmysoulwithoutfear.com