Ellen, Thanks for adding additional perspective to the discussion. You are probably correct in saying that no Christian group formally observes the Jewish Passover in the same way that Jews do. Still, Christian Pascha (the New Passover) includes all three meanings of Passover: saving the firsborn of Israel and freeing Israel from bondage, the Passover of Christ, and the opportunity for saving all mankind through the Blood of the Lamb.

We don't set a cup for Elijiah but we do honor Elihiah in the ancient Liturgy—The Liturgies of St. John Chrystostom and of St. James—and there is an Icon of the Prophet Elijiah on our Iconostasis, just to the north of the northern deacon's door. Christians do (or should) understand the Exodus story since the “One Holy Catholic and Apostolic Church” mentioned in the Nicene Creed holds itself to be the New Israel. We don't need to set a chair for Elijiah because all of heaven and earth (Elijiah included) celebrate the Liturgy and Eucharist with us, praising God and asking for His Mercy.

The Orthodox Church does not reenact the last supper as a symbolic act. There is nothing symbolic about our Liturgy or the Eucharist. I think Roman Catholics and Anglicans, at least, will tell you the same thing.

      - Mark