Ex 12:13, 1 Cor 5:7, Rom 8:1-2, 1 Pt 1:18-19, Heb 9:14
Pharaoh did not let the Israelites go until all the firstborn of Egypt died because the Egyptians did not apply the blood of the Passover lamb. By applying the blood of the Passover lamb on their doorposts, the Israelites escaped the last plague, the death of their firstborn, upon Egypt. (Ex 12:3-7, Ex 12:13)
Ex 12:3 Speak ye unto all the congregation of Israel, saying, In the tenth day of this month they shall take to them every man a lamb, according to the house of their fathers, a lamb for an house: 4 And if the household be too little for the lamb, let him and his neighbour next unto his house take it according to the number of the souls; every man according to his eating shall make your count for the lamb. 5 Your lamb shall be without blemish, a male of the first year: ye shall take it out from the sheep, or from the goats: 6 And ye shall keep it up until the fourteenth day of the same month: and the whole assembly of the congregation of Israel shall kill it in the evening. 7 And they shall take of the blood, and strike it on the two side posts and on the upper door post of the houses, wherein they shall eat it.
Ex 12:13 And the blood shall be to you for a token upon the houses where ye are: and when I see the blood, I will pass over you, and the plague shall not be upon you to destroy you, when I smite the land of Egypt.
The Passover Lamb at the time of the Exodus alludes to Christ. Christ was sacrificed to save us from all calamities. (1 Corinthians 5:7)
1 Corinthians 5:7 Purge out therefore the old leaven, that ye may be a new lump, as ye are unleavened. For even Christ our passover is sacrificed for us:
Those who believe in Jesus as the Christ are set free from the law of sin and death. (Romans 8:1-2, 1 Pet 1:18-19)
Romans 8:1 There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit. 2 For the law of the Spirit of life in Christ Jesus hath made me free from the law of sin and death.
1 Pet 1:18 Forasmuch as ye know that ye were not redeemed with corruptible things, as silver and gold, from your vain conversation received by tradition from your fathers; 19 But with the precious blood of Christ, as of a lamb without blemish and without spot:
We are cleansed from dead works by the blood of Christ, and we are able to serve God. (Heb 9:14)
Heb 9:14 How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God?