Passover is perhaps the most universally familiar of the seven feasts of Moses, as many have seen the famous Cecil B. DeMille film, The Ten Commandments, which depicts the death of the firstborn, subsequently commemorated as Passover. When God called Moses in Exodus 4, He predicted that Pharaoh would not let the Hebrews go until the death of the firstborn. The movie, although a classic in many respects, makes it sound like the death of the firstborn was an afterthought or was attributed to Pharaoh’s defiance. But if you study the Scripture, you realize God hardened Pharaoh’s heart and told Moses that after a series of plagues He cast upon the Egyptians, it would be the death of the firstborn that would finally convince Pharaoh to “let My people go!”
In Exodus 11 and 12, God told Moses that the Hebrews were to take an unblemished lamb, keep it with them for four days and then kill it. Then they were to take the blood of that lamb and put it on the doorposts and the lintels of their house that particular night, which on the Hebrew calendar was the 14th of Nisan. And that very night the Death Angel passed through Egypt, and houses that had the blood on the doorposts and on the lintels were “passed over” by the Death Angel and the firstborns inside were spared.
The doors of the homes that were covered with blood were protected. If you were the firstborn of an Egyptian and just visiting a home with the lamb’s blood on the doorpost, you were spared. If you were a firstborn Hebrew and not in the house with the blood, you died. In other words, the discriminating element was the blood, not that they were Jewish or Israeli or Egyptian. Those who followed the instructions were “covered” by the blood and “passed over.” The key principle was to be covered by the blood. The Death Angel followed his instructions: if there was blood, he could pass over.