The message of Passover is God is merciful. God created a way to demonstrate He was both merciful and just, by the grace He extended to the children of Israel through faith, and to you who have faith in Christ.

The children of Israel looked forward-to their Savior, the Messiah. And you look back to your Savior, the Messiah who is Christ the Lord.

The only way God deals with our sins and trespasses is through the blood of the Lamb of God. And God provides the means for atonement – both the sacrifice and man performing the right. Man does not initiate his relationship with God, only God does.

In God made that provision for sin and an act of grace. The shading of blood is the action required in making atonement for sin.

In fact under the Law almost everything is purified by means of blood, and without the shedding of blood there is neither release from sin and its guilt nor the remission of the due and merited punishment for sins. Hebrews‬ ‭9:22‬ ‬

For the life is in the blood, and I have given it for you upon the altar to make atonement for your souls; for it is the blood that makes atonement, by reason of the life which it represents. Romans. 3:24-26
‭‭Leviticus‬ ‭17:11‬ ‬

God Himself puts forward, before the eyes of all as a mercy seat and propitiation by the blood of His Lamb, which is the cleansing and life-giving sacrifice of atonement and reconciliation, each Child of Israel and you have to receive through faith. This was to show God's righteousness, because in His divine forbearance He had passed over and ignored former sins without punishment. Romans ‭3:25‬

From the very first Passover God's plan to save His people through substitution has not changed – Redemption through Blood. The Only Way God Deals with Sin Is through Blood.

At the first Passover, God showed His Mercy and Grace to the tribe of Israel who by Faith, God's Divine Persuasion through His Servant Moses, put blood on the doorpost of their houses. Exodus 12:13 says:

They believed the blood would be for a token or sign to them upon doorpost of the houses where they stayed, that when the LORD saw the blood, He would pass over the him, and no plague would come upon them to destroy them when the LORD smites the land of Egypt. [I Cor. 5:7; Heb. 11:28.]
‭‭Exodus‬ ‭12:13‬ ‬

And acted on what the LORD said, by taking a bunch of hits the, dipping it in the blood in a basin, and touching the lintels above the door and the two side poles with the blood; then instructed them not to go out of the house until morning. Exodus 12:22

In those who by faith acted on what God said, the LORD passed over them as he went through to slay the Egyptians; for He saw the blood upon the lintel and the two doorpost, and the LORD passed over the door and did not allow the destroyer to come into that house is slave them. Exodus 12:23

By faith, simple trust and confidence in God, He instituted and carried out the Passover and the sprinkling of the blood on the doorposts, so that the destroyer of the firstborn (the angel) might not touch those of the children of Israel. Exod 12:21-30
‭‭Hebrews‬ ‭11:28‬ ‬

God’s provision was simple: take a lamb. A mature male one-year-old and without blemish (Ex. 12:3–5). Examine it for four days to ensure there’s no flaw in it (12:6). And finally, on the 14th day of the month—the night the death angel kills the firstborn—kill that lamb.

The death of Christ is the fulfillment of all that was foreshadowed by the sacrifices in the Old Testament (1 Pet. 1:18-19; 1 Cor. 5:7; John 1:29, 36; 2 Cor. 5:21).

God sent His Son, born of a woman, born subject to the regulations of the Law, To purchase your freedom, to ransom, to redeem, to atone for you who was subject to the Law, that you might be adopted and have sonship conferred upon us and be recognized as God's son. Galatians‬ ‭4:4-5‬ ‬

Now you have died with Christ, who believe and you shall also live with Him. Romans ‭6:8‬

For you died, and your life is hidden with Christ in God. Colossians‬ ‭3:3‬ ‬

‭For our sake God made Christ to be sin Who knew no sin, so that in and through Him we might become the righteousness of God, what we ought to be, approved and acceptable and in right relationship with Him, by His goodness. 3Corinthians‬ ‭5:21‬ ‬