Question: In Exodus 14:4 it says “I will harden Pharaoh’s heart and he will come after them. I will triumph over Pharaoh and his entire army, and Egypt will know that I am God.’” Why would God want to show the Egyptians that he was the only God?
Answer: G-d wanted to show the world, not just the Egyptians, that He was the only true G-d. The Egyptians worshiped many G-d’s, and Pharoah himself thought that he was the G-d of the Nile River. The ten plagues and everything that surrounded that time period was a message to the world about the power of G-d. The Jews were strengthened and the Egyptians were terrified. The Jews were empowered and the world became aware of the power of the One, True G-d. The Jews were slaves, so there needed to be something drastic to change their mentality and make them realize that there was hope. The interaction of G-d in the world at that time helped to accomplish that.