Then you shall say to Pharaoh, "Thus says the LORD, Israel is my firstborn son, and I say to you, 'Let my son go that he may serve me.' If you refuse to let him go, behold, I will kill your firstborn son." --Exodus 4:22-23
I had not noticed till this week that God not only threatens to destroy Egypt's firstborn; he does so, more fundamentally, because Egypt has enslaved Yahweh's own firstborn, Israel. God gave Pharaoh a choice: my firstborn or yours. Pharaoh chose to continue his enslavement of God's firstborn, which led to Pharaoh's losing both--God's firstborn, Israel, and Pharaoh's firstborn.
But Pharaoh is not below us. His idolatry has been mirrored in my life and yours in a thousand ways just in this past week. Pharaoh chose self rather than God; so do you and I.
But for me (and for you?), God has not destroyed my own firstborn. He has destroyed his own firstborn. My idolatry is no less rebellious and sinister than Pharaoh's. But for some reason God has substituted his son for my sin rather than my son for my sin. As a result, Jesus has become the firstborn among a whole new order of life, into which I have been initiated by the Great Sacrifice.
He is the image of the invisible God, the firstborn of all creation. --Col 1:15
. . . Jesus Christ the faithful witness, the firstborn of the dead, and the ruler of kings on earth. To him who loves us and has freed us from our sins by his blood . . . --Rev 1:5-6