Although the vast majority of Jews and Christians celebrate their feasts without a overt recognition of their dependence, there would be no Easter without Passover.
The similarity of labels for Pesach and Pascha reflect their connections.
The two holidays usually coincide, but not exactly. Church fathers set Easter as the first Sunday after the full moon that occurs after the equinox, meant to assure that Easter does not occur on the day of the Seder which happens on the day of the full moon, i.e., the 15th of Nisan in the Hebrew lunar calendar. The timing of Easter has been tweaked a bit and there is a difference in the calendars used by Western and Eastern Christians, but the principal remains that Easter comes along with Passover, but not at the beginning of the Jewish holiday.
Leaving aside the questions that must be raised about the accuracy of the histories provided in Exodus or the Gospels, both are good stories that have passed the test of time.
The dependence of the holidays is not mutual. Passover does not depend on Easter, but there would be no Easter without Passover, or what Jesus did at the time of the Jewish holiday.
The Last Supper was the Seder celebrated by the Jew called Jesus with his closest followers, and the crimes for which he was executed dealt with his choice of the Passover feast to create a scene on the Temple Mount. Central to the story told by historians who try to find reality in the Gospels is the riot he may have provoked in the presence of a couple hundred thousand pilgrims, many from distant lands, all anxious to change their money so they could purchase sacrifices for one of the principal rites of the Jewish calendar. Overturning the tables of the money changers, as well as assertions about his own holy status was too much for the rabbis and for Roman officials concerned above all with keeping order.
It was not an ordinary crime, for which rabbinical judges would have pondered at length issues of motivation, witnesses, and the accused having been warned sufficiently to desist. It was a challenge against the Judaic establishment by a known radical, of the kind who has been seen time and again in Jewish history, and whose equivalents can be found in good universities where Jews study. If we believe the Gospels, there was a speedy trial and implementation of an extreme verdict.
The themes of both holidays are similar. Passover's story of freedom from slavery is not all that different from Easter's story of resurrection and eternal hope. Anthropologists view them both as spring festivals, with rebirth for people as well as vegitation.
There is also animosity inherent in the holidays. The linkage of Passover and Easter was a time a trial for European Jews. It was the season of being accused of killing Christ, and pogroms whipped up by preachers or produced by simple Christians often looking for a reason to take vengeance on Jews.
The traditional Passover Haggadah includes a passage left out, explained away, or replaced with something much different in the ceremonies of those embarrassed by the darker sides of Jewish history. It begins
שפך חמתך אל הגוים אשר לא ידעוך ועל ממלכות אשר בשמך לא קראו . . .
Pour out Your wrath upon the nations that do not acknowledge You, and upon the kingdoms that do not call upon Your Name. For they have devoured Jacob and laid waste his habitation.Pour out Your indignation upon them, and let the wrath of Your anger overtake them. Pursue them with anger, and destroy them from beneath the heavens of the Lord.
The source of the language is Biblical, and thus precedes Christian anti-Semitism, but who knows the meaning given the phrase by European Jews reciting it in the Middle Ages, Jews in 21th century America, or Israel.
The presence of New York's Roman Catholic Archbishop, along with children from Catholic and Jewish schools, along with Abraham Foxman at a Seder organized by the Anti-Defamation League shows that traditional Christian anti-Semitism is now a regretted and rejected element of things past, at least in the doctrine of the largest and most tightly organized Christian Church.
One can find elements of the Christian tradition in the anti-Semitism of American Blacks, but theirs is more clearly animosity toward the wealthy than toward those who killed Christ. It comes along with the adoption in Black culture of the Passover story about the freedom for slaves.
Go down MosesWay down in Egypt landTell all Pharaohs to. . .When Israel was in Egypt land. . .Oppressed so hard they could not standLet my people go.
Passover and Easter do not exhaust the subject of anti-Semitism. More prominent today is Muslim anti-Semitism, with its roots in the refusal of Arabian Jews to accept Muhammad as a prophet, added to modern enthusiasm for Palestine, and Israel's offense against the notion of an Islamic Middle East or an Islamic world. The anti-Semitism of American Blacks--among those who have adopted Islam as well as secular activists--includes an element of opposition of Israel/Jews for the repression/occupation of Palestine.
Revising the Haggadah to reflect one's own view of Passover is well established in Jewish tradition. There are versions created by kibbutzim, feminists, environmentalists, and advocates of peace, with variation within each of these categories.
In the place of "pour out you wrath" there are Haggadoth with
Pour out your love on the nations who know YouAnd on kingdoms who call Your name.For the good which they do for the seed of JacobAnd they shield Your people Israel from their enemies.May they merit to see the good of Your chosenAnd to rejoice in the joy of Your nation.We can assume that one of the kinder versions of the Haggadah was employed in the ceremony that included New York's Archbishop.
Among the better holiday greetings is a cartoon showing Moses reading from his GPS to cross the Red Sea, turn right to Mt Sinai, and arrive at Promised Land destination in 40 years.
Wherever you find mind and body at this confluence of cultures, enjoy the sentiments, the song, the wine and the food, but don't overdo on the latter. חג שמח