Why do we open the door for Elijah?

Search: why do we open the door for elijah

Why: Chag Pesach Sameach, yeladim.

Answer: Elijah will herald the coming of the Messiah. If we set out some extra wine during the Seder and open the door, hopefully he will appear to announce the Messianic era and the redemption of man.

Elijah's exploits are in the Book of Kings. He is a prophet who does not have his own book, and he doesn't prophesy about the future. He publicly denounced King Ahab and Queen Jezebel for immorality, including the murder of Naboth to obtain a vineyard. He accused the Israelites of abandoning God. He challenged the priests of Baal to a duel between their gods.

Most importantly, Elijah never died. Instead, he was carried to heaven in a whirlwind by a "fiery chariot with fiery horses" (II Kings 2:11). The Jewish concept of the Messianic age includes the resurrection of the dead, and here's someone who won't need to be resurrected. That, plus his fiery stance against injustice, led to the belief that Elijah will usher in the Messianic age.

Source: The Straight Dope

The More You Know: Elijah is one of 2 characters in the Torah who don't die but are taken directly to Heaven. The other is Enoch, who "walked with God, and then he was no more, for God took him" (Gen 5:24).