The LORD promised that He would deliver the Israelites. In every other case, the LORD announced his plan beforehand to Pharaoh, so that He would know that the LORD is God. After nine plagues, Pharaoh refused even to hear from Moses again. So the LORD revealed His Plan to the Israelites.
The LORD warned that He would pass through the Land of Egypt and bring judgment by striking down the firstborn of man and beast. This final blow would serve also as a judgement upon the false gods of Egypt, a final proof that they were powerless against the LORD.
When some people read these words, they shake their heads and ask: “How could a loving God do such a thing?” The simple answer is that God is also just, holy and true. The Pharaoh and his people had defied Him and rejected Him and He chose to judge them for their unbelief. If we remember that God is just and holy; we don’t accuse him of making a mistake.
We find here more than words of judgment. We also find here words of mercy and a promise of deliverance. We find the God-given meaning of the Passover. For the LORD promised the Israelites that He would "pass over" them and not bring judgment upon them— because of the blood on their houses, the blood of the passover lamb.
It is Jesus’ blood, the blood of the Lamb of God, that delivers us from sin, death and eternal judgment! Let us rejoice today in God’s mercy!