Bumping for later. We have a Messianic Jew (believes in Christ as Messiah) that is giving talks at our church. We have been looking at the various Jewish holidays and how they fit in with the Christian holidays. Not that the Christians wanted to “fit in”, but that the “Christian” events happened on the Jewish holidays. He was saying how the ancient rituals of the Passover Feast (Last Supper) can add lots of meaning to a Christian, but is not “mandatory”.
As you said, Christian events happen on God's holy days. Christ was killed on Passover. The church was established on Pentecost. In God's prophetic timetable we are in the long season between the spring holy days and the fall holy days. Future events such as the return of Christ will likely happen on God's holy days.
One significant aspect of Passover prior to the Resurrection as opposed to after the Resurrection is that sinners were “passed over” prior to His perfect sacrifice. When He made that sacrifice, He made it once and for all, not to be repeated eternally, but one performance of that sacrifice, thereby changing the state present to believers after the Resurrection.
This has been a point of contention between Protestants and Roman Catholics for centuries, though, in that the tradition of transubstantiation attempts to repeat Christ’s sacrifice at every Mass, instead of relying upon the one Perfect sacrifice made on the Cross for righteousness before God.