Passover is the festival which commemorates and celebrates the night that the Israelites gained their freedom from Egypt, and left on their journey that would eventually take them across the Red Sea, and to the promised land.
It is celebrated by Jews starting on the 14th day of Nisan (which would be the 14th day after the new moon, and so it is not always on the same date as our Gregorian calendar) and it recounts how God sent His ten plagues upon Egypt to convince the Pharaoh to let the Israelites go. The word “Passover” is a reference to the 10th plague, which was to inflict the Egyptians with the death of their firstborn, but would “passover” and not effect the house of the Hebrews who had put the blood of a lamb on their doorposts and lintels to their homes.
One of the distinctives that is part of the observation of Passover is the purging to anything with leaven or “chametz” from the house. This is symbolic of how the Israelites left Egypt in such haste, there was no time for bread that they baked to rise. In Rabbinic tradition, a family typically would scour the home for anything with leaven on the first night of Passover and destroy it.
The actual Passover Seder has a number of ceremonial foods that are enjoyed. Including matzah (unleavened bread), bitter herbs (to commemorate the bitter slavery endured by the Israelites), and a traditional meal, accompanied by wine of grape juice. The specific order and meaning of the foods is explained to the participants in the recitation of the Haggadah, which is a liturgy telling of the story of the Exodus from Egypt.
It is a strange irony in contemporary times that the Passover Seder (or “Pesach”) is celebrated by Jews almost exclusively. Jesus’ last supper was a Passover Seder, and his words “Do this in remembrance of me” would be indicative of the fact that he expected his disciples to be observing passover Seders in perpetuity after he was gone.
We see later in the New Testament, after Jesus had ascended to heaven that the apostle Paul specifically kept observing the Passover (Acts 18:21, Acts 20:6). And in I Corinthians 5:7, 8, he tells the believers in Corinth (which was a congregation both of Jews and Gentiles) that they were to
“cleanse out, therefore, the old leaven, that ye may be a new lump, according as ye are unleavened, for also our passover for us was sacrificed–Christ, so that we may keep the feast, not with old leaven, nor with the leaven of evil and wickedness, but with unleavened food of sincerity and truth.”
The early church saw the Pesach as one of the clearest types or foreshadowings of the passion of Christ, and the symbolism in the sedar as pointing to Christ. Thus, as evidenced by the early church fathers, the church observed the Pesach for at least two hundred years after the advent of Christ, with just some minor disagreement as to the exact day.
By the early 4th century, however, in making a definitive split with Judaism, some church leaders opted for their own method of determining when to celebrate the passion and resurrection of Christ, and broke with the biblical and apostolic practice.
The new holiday eventually became fused to some of the other local traditions, including the Spring festival of Oester, ( a spring fertility celebration) and the name “Easter” became widely accepted, along with the other trappings of that holiday, such as colored eggs, and rabbits.