“For I will pass through the land of Egypt that night, and I will strike all the firstborn in the land of Egypt, both man and beast; and on all the gods of Egypt I will execute judgments: I am the Lord.” Exodus 12:12
The One true God is at war with all pretenders to His throne. Throughout the Bible we see the Lord demonstrating His supremacy over all other gods. In the Exodus from Egypt God sends ten plagues to humble proud Pharaoh and prove both to the Egyptians and to the Israelites the fullness of His glory.
Then the Lord said to Moses, “Go in to Pharaoh, for I have hardened his heart and the heart of his servants, that I may show these signs of mine among them, 2 and that you may tell in the hearing of your son and of your grandson how I have dealt harshly with the Egyptians and what signs I have done among them, that you may know that I am the Lord.” Exodus 10:1-2
Here is one chart showing how each plague highlighted the power of the Lord of Israel over one or more of Egypt’s gods.
This article provides a more detailed explanation.
“The fact that God defeated the gods of the Egyptians in general, however, does not give interpreters license to read into the narrative a specific blow-by-blow list of the supposed deities whom Yahweh defeated. There are historical problems with correlating each plague with a particular ancient Egyptian deity. Many of the gods and goddesses had multiple functions or responsibilities, making it difficult to know which deity was being attacked by a given sign.”
Pastor Colin Smith says it this way:
God was saying to Pharaoh, ‘You worship Osiris, saying that the Nile sustains you, but I will turn the Nile into a lifeless swamp. You worship Hekt, the goddess of birth, who is depicted as a frog, but I will give birth to so many frogs that you will wish you had never known her. You worship Ra, saying that the sun will shine on you, but I will turn the sun to darkness. What you have put in my place will become a plague to you.”
This theme continues in the New Testament with the central gospel message: “Jesus Christ is Lord.” Just as Israelite families were saved by the blood of a lamb, so the Lamb of God who was crucified was raised from the dead in proof of His supremacy over everything, everyone and all other gods.
“For by him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things were created through him and for him. And he is before all things, and in him all things hold together. And he is the head of the body, the church. He is the beginning, the firstborn from the dead, that in everything he might be preeminent.” Colossians 1:16-18