Why did they smear lambs blood on doors according to the bible?

Answer 1

This was to show God that the hebrews trusted him and in doing so he or the angels of death God had sent to kill the first born child would "Passover" there door if they did as they were instructed to do with the lamb blood, thus creating the christian celebration of passover.

Answer 2

It is because in The Bible there are ten plagues and it was believed that the only way to be spared from these plagues and have the Angel of Death pass by your home was to sacrifice a lamb and use its blood to paint your doorpost.

Answer 3

In the Old Testament, God told Moses during the ten plaques, that in the last one a lamb should be sacrificed and the blood smeared on the front door, and the angel of death , would then pass that house. But the Egyptians had no blood on their doors, so their first born died.

Answer 4

The blood on the door-lintels (Exodus ch.12) served as a demonstration that the Israelites had accepted and were observing God's commands concerning the Passover sacrifice (ibid; and Rashi commentary). Also, since the Egyptians worshiped sheep, the slaughtering of sheep as a sacrifice by the Israelites showed that the Israelites were flouting the Egyptians' idolatry; and the placing of the blood publicized this.