Principle
God gave Israel a memorial called Passover to remind them of how He spared their firstborn children on the night of the final plague upon Egypt, the night Israel was set free.
Explanation
As GOD was about to bring that dreadful final plague upon Egypt, He gave Israel a memorial to remind them. He called that memorial Passover.
1 Now the Lord spoke to Moses and Aaron in the land of Egypt, saying, 2 “This month shall be your beginning of months; it shall be the first month of the year to you. 3 Speak to all the congregation of the children of Israel, saying, ‘On the tenth day of this month every man shall take for himself a lamb, according to the family households, a lamb for each home. 4 If there be too few in a household, let him and his neighbor next to his house take it according to the number of souls; he will make his count in lambs according to the needs of each one. 5 Your lamb shall be without blemish, a male of the first year. You shall take it from the sheep or the kids. 6 Then you shall keep it until the fourteenth day of the same month, and the whole assembly of the congregation of Israel shall kill it at twilight. 7 Then 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. 8 They shall eat the flesh on that night, roasted in fire; with unleavened bread and bitter herbs they shall eat it. 9 Do not eat it raw, nor boiled at all with water, but roasted in fire—its head with its legs and its entrails. 10 You shall let none of it remain until morning, nor shall you break a bone of it; and what remains of it until morning you shall burn with fire. 11 Thus you shall eat it: with a belt on your waist, your sandals on your feet, and your staff in your hand. You shall eat it in haste. It is the Lord's Pascha. 12 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 vengeance: I am the Lord. 13 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. 14 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.
15 ‘Seven days you shall eat unleavened bread. On the first day you shall remove leaven from your houses. For whoever eats leavened bread from the first day until the seventh day, that soul shall be cut off from Israel. 16 On the first day there shall be a holy convocation, and on the seventh day there shall be a holy convocation for you. No servile work shall be done on them; and whatever must be done by each soul, this only shall be done by you. 17 So you shall keep this commandment, for on this same day I will bring your army out of the land of Egypt. Therefore, you shall observe this day throughout your generations as an everlasting ordinance. 18 In the first month, on the fourteenth day of the month at evening, you shall eat unleavened bread, until the twenty-first day of the month at evening. 19 For seven days no leaven shall be found in your houses, since whoever eats what is leavened, that soul shall be cut off from the congregation of Israel, whether he is a stranger or a native of the land. 20 You shall eat nothing leavened; in all your dwellings you shall eat unleavened bread.’”
(Exodus 12 1-20 OSB)
The Passover has multiple deep meanings. Let's start by applying the Primary Audience Principle.
The First Passover
For the individual Israelites to whom Moses spoke GOD's instructions on that day, the Passover served firstly as a test of faith. Keeping a lamb or goat for four days, killing it, and spreading its blood above your front door seems, at minimum, weird, if not crazy.
Would each Israelite family trust and obey? In this case, yes they did. (After all, these people had seen some amazing and wild miracles in their recent past!)
Secondly, the Passover meal served as food for physical strength. Israel was about to leave on a long and difficult journey. They needed food to sustain their bodies.
Thirdly, the Passover marked the night of their departure from captivity, the end of their slavery. According to Exodus 12:40 (LXX), Israel had been sojourning in Canaan and Egypt a total of 430 years. The apostle Paul wrote in Galatians 3:17 that it was 430 years from the time GOD promised Abraham regarding his future seed until the time that the Law of Moses was given.
Fourthly, the Passover marked the fulfillment of GOD's prophecy revealed through Moses regarding Israel's deliverance. When Moses first went to Pharaoh, things hadn't gone so well. The children of Israel were angry at Moses because Pharaoh had rejected GOD's message and, instead, made life harder for Israel temporarily.
Fifthly, the Passover marked the distinction between GOD's people and the rest of the world—Egypt, in this case. Beforehand, Moses warned Pharaoh about this:
4 Then Moses said to Pharaoh, “Thus says the Lord: ‘About midnight I will go out into the midst of Egypt; 5 and all the firstborn in the land of Egypt shall die, from the firstborn of Pharaoh who sits on his throne even to the firstborn of the female servant behind the handmill, and all the firstborn of the cattle. 6 Then there shall be a great cry throughout all the land of Egypt such as was not like it before, nor shall be like it again. 7 But against not even one of the descendants of Israel, be it man or cattle, shall a dog snarl its tongue, that you may know the Lord shall make a wide distinction between the Egyptians and Israel.’ 8 And all these your servants shall come down to me and bow down to me, saying, ‘Go from here, and all the people who follow you.’ After that I will go out.” Then he went out from Pharaoh in great anger.
(Exodus 11:4-8 OSB)
And sixthly, the Passover marked the end of GOD's supremacy (passing over) the gods of Egypt.
Ongoing Meaning
GOD gave Israel the Passover meal as a part of the Feast of Unleavened Bread, one of three annual feasts for which the Israelites would eventually assemble in Jerusalem.
The Passover meal served as an annual reminder to the Israelites of what GOD had done for Israel in rescuing them from slavery and taking them to their future land.
And the Passover also served as a shadow of the future offering of Jesus as the Lamb of God who takes away the sins of the world (see John 1:29). The Christian tradition of Easter originates from the Jewish Passover.
