After 400 years, the people thought the Egyptian Gods were powerful. Now God will demonstrate to the Egyptians and the Hebrews that God alone is all powerful.
Exodus 5:1-2, 22-23 NRSV
Afterward Moses and Aaron went to Pharaoh and said, “Thus says the Lord, the God of Israel, ‘Let my people go, so that they may celebrate a festival to me in the wilderness.’” 2 But Pharaoh said, “Who is the Lord, that I should heed him and let Israel go? I do not know