Why do we open the door for Elijah at the Passover seder? In the Bible, Elijah does not die (he goes up to heaven in a chariot — see 2 Kings, chapter 2). Therefore he is the prophet our tradition assumes will return to announce the coming of the Messiah.
The cup of Elijah stands on the table because of an unresolved Talmudic dispute over whether there should be four or five cups of wine at the seder table. We use four. If Elijah drinks, we learn that five is the correct answer. The Rabbis teach that when Elijah comes, all remaining disputes of law will be resolved. So keep your eye on that cup.
Finally, there are particular reasons for the special times Elijah is anticipated — at a brit milah, the end of Shabbat, the end of Yom Kippur and Passover. But also, they are all family times. We are told of the Messiah that: “He will turn the hearts of the parents to their children, and the hearts of the children to their parents” [Malachi 4:6]. So if on the night of the seder you are gathered in joy with family, you have experienced a taste of the Messianic Age, even if Elijah has not yet arrived. Chag Kasher V’sameach.
Rabbi David Wolpe is spiritual leader of Sinai Temple in Los Angeles. Follow him on Twitter: @RabbiWolpe. His latest book is “David: The Divided Heart” (Yale University Press).