The Christian Easter (or Passover) rests entirely on the Jewish holiday Pesach. During the Feast of Unleavened Bread in biblical times, the Jews gathered at the Temple in Jerusalem to celebrate the feast and sacrifice the Passover lamb. The Hebrew word pesach, which means "to pass by/over “, refers to how the angel of death in Exodus passed over all the houses where the doorposts had been smeared with the blood of a sacrificed lamb. It meant that the first-born Jewish male children were saved, while the first-born sons in Egyptian homes perished.
The vicarious sacrifice of the Passover lamb as the salvation from the angel of death is the very foundation and starting point of what Jesus did as the Lamb of God in his vicarious death for mankind.
Even Pentecost rests in a similar way on the Jewish holiday of Shavuot, which is both a harvest festival and is celebrated in memory of how God gave the Jews the Ten Commandments on Mount Sinai. The miracle of Pentecost occurred when the disciples celebrated Shavuot - the law was written in their hearts by the Holy Spirit and the first fruits of people who turned to the Lord could be gathered.