When the Lord tells Moses to announce to Pharaoh that Israel is his firstborn son (Exodus 4:22), he uses a kind of language that immediately lifts our minds to Jesus Christ, the only begotten, eternal, natural Son of God. Just as the Lord called his son Israel out of Egypt (Hosea 11:1), so he would also ensure that Jesus Christ would complete his work and obtain the inheritance. As the continuation of the covenant people of God, the church today is also like a firstborn son to God, although unlike Israel who only anticipated the coming of Christ, we are united to God’s only begotten Son by true faith as adopted children.
21 And the LORD said to Moses, “When you go back to Egypt, see that you do before Pharaoh all the miracles that I have put in your power. But I will harden his heart, so that he will not let the people go.