The history of The Passover is that Israel were in Egypt enduring cruel slavery. They were there because of famine and had gone to buy food.

In the process they had found favour with the Pharaoh because of  Joseph, who was the son of Jacob, Israel's patriarch.

Some years earlier Joseph, as a slave in Egypt, had prophesied a severe famine, had led the preparations to suessfully cope with it. Consequently, the Pharaoh honoured Israel and allowed them to stay (Genesis 47'27 onwards).

They prospered. But a later Pharaoh saw them as a national threat and made them slaves.

Relentless cruelty was inflicted on them and they were desperate for deliverance. They called out to God and He raised up Moses to approach the Pharoah on their behalf:

"... you shall say to him, ‘The Lord God of the Hebrews has sent me to you, saying, "Let My people go, that they may serve Me in the wilderness'," Exodus 7'16.

The Pharaoh refused Moses on ten occasions. Each denial resulted in a plague coming upon the country. The final one would result in The Passover and Israel's freedom.

The Lord gave Moses these instructions:

"Speak to all the congregation of Israel, saying: ‘On the tenth day of this month every man shall take for himself a lamb, according to the house of his father, a lamb for a house.

Your lamb shall be without blemish, a male of the first year. You may take it from the sheep or from the goats.

Now you shall keep it until the fourteenth day of the same month. Then the whole assembly of the congregation of Israel shall kill it at twilight.

And they shall take some of the blood and put it on the two doorposts and on the lintel of the houses where they eat it.

Then they shall eat the flesh on that night; roasted in fire, with unleavened bread and with bitter herbs they shall eat it.

Do not eat it raw, nor boiled at all with water, but roasted in fire - its head with its legs and its entrails.

You shall let none of it remain until morning, and what remains of it until morning you shall burn with fire.

And thus you shall eat it: with a belt on your waist, your sandals on your feet, and your staff in your hand. So you shall eat it in haste. It is the Lord's Passover.

For I will pass through the land of Egypt on that night, and will strike all the firstborn in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgment: I am the Lord.

Now the blood shall be a sign for you on the houses where you are. And when I see the blood, I will pass over you; and the plague shall not be on you to destroy you when I strike the land of Egypt.

So this day shall be to you a memorial; and you shall keep it as a feast to the Lord throughout your generations. You shall keep it as a feast by an everlasting ordinance'," Exodus 12'3,5-14.

"The Lord's Passover". Jews still celebrate it as part of their Feast of Unleavened Bread for seven days annually, usually in April.

It's all about deliverance from slavery to freedom. Their's was physical, ours was spiritual.