Back in the old days when the Israelites were still slaved in Egypt, God sent Moses to free them from slavery. Unfortunately the Pharaoh kept going back on his word. So God sent plagues and serve catastrophes to make His point. In a big event in Exodus 12:5-13, God told the Israelites to sacrifice an unblemished lamb and smear its blood on the door posts. The angel of death would then pass over the houses those houses. Thus God saved the children of Israel from death.
“Your lamb shall be without blemish, a male of the first year: ye shall take it out from the sheep, or from the goats…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” (Exodus 12:5,7).
God gave them the instruction to save the lives of the children of Israel in Egypt.
“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” (Exodus 12:13).
This is a picture of what Christ did for us on the cross.
“The next day John seeth Jesus coming unto him, and saith, Behold the Lamb of God, which taketh away the sin of the world” (John 1:29).
When Jesus Christ died on the cross to save us from our sins, He was the perfect lamb of sacrifice for us.
“For God so loved the world, that He gave His only begotten Son, that whosoever believeth in Him should not perish, but have everlasting life” (John 3:16).