Like the plague of flies, the plagues of cattle death and boils only bother the Egyptians, not the Hebrews. God is clear about His objective—to show the Egyptians His power and to proclaim His own name through all the earth. God’s actions are not merely performed to free people from slavery—which we are often guilty of making the story about. It is about God’s glory. If God would have merely freed the people from slavery, put forth His hand and struck the Egyptians with pestilence, Egypt would have been cut off from the earth and the Hebrews would be free. God’s goal is not to destroy a whole people group. Instead, He wants to be known in Egypt and in the whole of the world. Even though God has done everything He has done, Pharaoh still exalts himself against the Hebrews.
As the Egyptian cattle die and the Egyptians develop boils on their skin, the Egyptian deities, Hathor and Isis, are slain. Yahweh is actually the one with power. His indictment against Pharaoh is self exaltation. Here, we learn something about any false religion. False religion provides a pretense and system whereby people can exalt themselves. True religion is humbling and exalts God alone.
So, any system whereby we worship a deity in order to gain from that deity is a false system. Any system that uses a deity to get people to act a certain way is a false system. Any system that exalts people instead of God is a false system—and God is at war with that kind of system.