Hi, Steelmaker. I am an Orthodox Jew. Will you accept that I know something of my religion and its beliefs? Shain is correct on the point regarding Passover. There are two separate things going on here. The first is the historical event, in which the Jews in Egypt tied up the symbol of the Egyptian deity for several days and then slaughtered it - and consequently were spared when the Angel of Death passed over their houses. That happened once.

The second is the decree that the entire exodus, starting from the above event, be remembered for seven days that begin with eating the paschal offering (in memory of the original act of defiance and its results) and include a prohibition against eating leavened bread (in memory of our ancestors' haste preventing them from waiting for the bread to rise). The Bible calls this the "feast of Matzah" (or something similar - I am translating from the Hebrew). The name "Passover" is what we call it.

My rabbi once explained in a homily how this represents a mutual respect between G-d and the Jewish people: He calls the festival by what we do, and we call it by what He did.