“Then they shall take some of the blood and put it on the two doorposts and the lintel of the houses in which they eat it.” (Exodus 12:7, ESV)

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 no plague will befall you to destroy you, when I strike the land of Egypt.” (Exodus 12:13, ESV)

Could there be any richer symbology of the cross than the Israelites as they prepared for the Exodus?  The avenging Angel of the Lord was coming that night and the firstborn of everything that breathed in Egypt would be killed.  The only way to prevent this 10th plague from affecting one’s family was to act.  A lamb was to be sacrificed and the blood of that lamb was to be spread around the door of the dwelling and when the Angel of the Lord saw this, he would pass over “and no plague will befall you to destroy you.”

So far as we know every Israelite obeyed and every family was spared from destruction.  On the other hand Egypt was devastated.  So thorough was the destruction that Pharaoh, perhaps the most stubborn man in the history of the world, sent a message to Moses that everything and everyone could go, and everything did go.

We simply cannot understand John the Baptist’s words in John 1.29 apart from the event of the Exodus:

The next day he saw Jesus coming toward him, and said, “Behold, the Lamb of God, who takes away the sin of the world!” (John 1:29, ESV)

The threat from Pharaoh was ended.  The people were free.  They would be continuously celebrating the events of the Exodus until Jesus came and really did take away the sins of the world with his own blood at the cross.