No one knows for sure. Today, the celebration of Jesus’ resurrection is known as Easter. Easter does not have a fixed date. It is celebrated on the first Sunday after the first full moon after the spring equinox. In the early days of the church, Christian leaders wanted to honor the death and resurrection of Jesus soon after Passover, because the Bible describes how Jesus’ death and resurrection took place following Passover. The Jewish calendar is based on lunar cycles, so the date of Passover changes every year. To make sure the date of Jesus’ resurrection always came after Passover, the church made that date changeable as well.