What is the ultimate purpose and significance of Passover or Pesach ?
The ultimate purpose of Passover or Pesach is to create a connection between ourselves and G-d for the purpose of creating a relationship with G-d by fulfilling the biblical commandment from G-d to the Hebrews ("mitzvah" means "commandment" in Hebrew) of commemorating and celebrating "Chag Ha-Matzot" ("The Festival of Unleavened Bread" in Hebrew) which is the name given to this festival in the original Hebrew version of the Hebrew Bible; the words Passover or Pesach by themselves are never mentioned as the name for this festival in the Hebrew Bible. However, in Shemot or Exodus 34:25, "The Festival of the Passover" ("Chag Ha-Pesach" in Hebrew) is mentioned and is associated and connected with Chag Ha-Matzot in that it occurred on the day immediately preceding Chag Ha-Matzot and that the Korban Pesach, or Passover sacrifice, which was sacrificed in the late afternoon on Chag Ha-Pesach, was eaten not long after, during the first evening of Chag Ha-Matzot, as the Jewish day begins either at sunset or at nightfall, depending on the authoritative rabbinical opinion one follows. Inherent in this mitzvah is to not only tell the story of Pesach or Passover and its timeless messages at the Seder table on an annual basis but to re-tell the story of Passover or Pesach and its timeless messages to as many people as possible and in the manner in which they would understand the story and its messages, meaning according to their social, religious, and/or political philosophies so that all of humanity can benefit from the hope and encouragement that these messages contain.
But why is the ultimate purpose of Passover or Pesach rooted in the obligation to annually commemorate and celebrate the Festival of Unleavened Bread by telling the Passover/Pesach story? The reason why we are obligated to fulfill the commandment of telling the Pesach or Passover story is stated in a declaration in the Haggadah, the "instruction manual" for conducting the Seder, the festive meal that opens the Passover/Pesach festival on the first evening only for those that celebrate Passover/Pesach for 7 days (most Reform Jews, some Conservative Jews, and Jews living in Israel), and on the first two evenings for those that celebrate Passover/Pesach for eight days (Jews living outside Israel, except for most Reform Jews and some Conservative Jews): In the Haggadah, the Hebrew phrase, "Avadim Hayinu", meaning "We were slaves", is the title of the first three words of the declaration: "We were slaves unto Pharaoh in Egypt, and Hashem our G-d took us out from there with a strong hand and an outstretched arm". Therefore, this declaration is the fundamental reason why we are obligated to tell the Passover/Pesach story: we are expressing our enormous gratitude to G-d for redeeming us, for had G-d not redeemed us, we would still be in Egypt. This is why the Exodus story applies to us today and in every generation, past and future. Therefore, at the Seder, and, by extension, in everyday life, we are encouraged to experience and feel as if we ourselves had personally embarked on the Exodus from Egypt to freedom. The purpose of the Seder rituals is to activate this feeling of transitioning from slavery to freedom so that we are constantly aware of it both at the Seder and in daily life. This helps in elevating one's sense of empathy towards oneself and others, for the challenge still remains to free those still living under political, physical, and spiritual oppression, be it oppression under a ruler, or personal oppression from one's psychological state.
By fulfilling the purpose of Passover or Pesach, the primary message of believing in and therefore relying on the One, True, Omnipresent G-d as being one's deliverer from physical, political, and ultimately spiritual oppression as well as the giver of one's freedom in their place has throughout the generations and continues to serve as a catalyst for not only the Jewish people but for all humanity to work together to eradicate human oppression in all its forms in all societies. The significance of Passover or Pesach lies in the belief and proactive willingness of the Jewish people to work toward achieving social justice in all societies and this principle is at the heart of Judaism itself since Judaism is not only a monotheistic religion, but an ethically monotheistic religion.
The significance of Passover or Pesach is also reflected in its being the oldest festival/holiday in Judaism which originally occurred in the first month of the Jewish calendar, and therefore symbolized a new beginning for the Hebrews as being one nation that emerged from a loose confederation of 12 tribes while toiling as slaves in ancient Egypt. It is no wonder that G-d commanded the Hebrews to mark this monumental event by commemorating the first Passover or Pesach in every generation from that point onward. The association of the One, True, Omnipresent G-d with the new status of the Hebrews as one, free nation occurring in the first month meant and continues to mean that the ethical foundation and principles of social justice in Hebraism and later on, Judaism were rooted in the Exodus from Egypt.
Although the words Passover or Pesach by themselves are never mentioned as the name for this festival in the Hebrew Bible, the English name Passover [ultimately derived from the Hebrew word Pasach, meaning either to "skip over (or on)" or to "pass over (or on)"] and the Hebrew word Pesach became interpreted and associated with Chag Ha-Matzot in the Hebrew Bible and eventually both words became the colloquial names that were used for Chag Ha-Matzot among the Jewish people.
As mentioned, another primary purpose of Passover or Pesach is to tell the story of Passover or Pesach on an annual basis and this is done as part of the festive meal that opens Passover or Pesach, known as the Seder meal. For Jews who celebrate Passover or Pesach for seven days, the Seder meal is held only on the first evening of Passover or Pesach; for Jews who celebrate Passover or Pesach for eight days, there are two Seder meals and each are celebrated in an identical way: the first is held on the first evening of Passover or Pesach and the second is held on the second evening of Passover or Pesach. The purpose of telling the Passover story or Pesach story is to remind all in attendance at the Seder meal that the messages and lessons of the story, albeit ancient in their age, apply in all generations: past, present, and future, and not only to the Jewish people, but to all humanity. In fact, the messages and lessons of Passover or Pesach are considered to be so important in Judaism that it is considered a greater mitzvah (in this context, a mitzvah colloquially means a "good deed" as in the mitzvah or commandment of G-d being a good deed) to not only fulfill the obligation to tell the story of Passover or Pesach at the Seder meal, but after the Seder meal, to re-tell the Passover or Pesach story and its messages and lessons to as many people as possible, be it Jewish people or those from other faiths, and according to the social, political, and/or religious philosophy that the listeners understand to ensure they comprehend all that is being said. For not only are Jewish people obligated to help spread the message of hope and encouragement to all those who are currently living under physical and political oppression, they are obligated to work toward that end in whichever way they can, since they are aware that in the Passover or Pesach story, they were once slaves in Egypt, and are reminded of that on annual basis during the Passover or Pesach festival. Therefore, another purpose and significance of Passover or Pesach lies in recounting the events of the first Passover or Pesach at the festive Seder meal as if he or she had personally been involved in those events so that we feel more aware of the significance of the events and thus gain more empathy toward those still living under oppression and consequently work toward gaining their political and physical freedom as well.