Exodus 12:23 For the LORD will pass through to smite the Egyptians; and when he seeth the blood upon the lintel, and on the two side posts, the LORD will pass over the door, and will not suffer the destroyer to come in unto your houses to smite you.
God is going to send death over all of Egypt but there is a difference between His people and others. He will not take the lives of their first born children. Rather He will allow them to have a substitute die in their place. The blood of the lamb will be on their door and He will pass over!
One of the greatest joys we have in the world is knowing that our sin debt was paid by another. Jesus took our place. We know that God is satisfied with the work of Jesus on the cross.
We stand redeemed and in right relationship with God because of what Jesus did on the cross of Calvary!