God proved that he's the only God in the midst of a nation that believe in so many God's in the Egypt. https://youtu.be/PYmC6Xevnv8?si=GuODNY2l2V_V5khW
You remember the ten commandments? you remember the story of moses,The story of exodus and the story in Genesis wherein the isrealites the seeds of Abraham in the start of the history of the isrealites as a people they joined in Egypt for 430 years it because of the famine that started during the time of Joseph the son of jacob. They where forced by circumstances to join in egypt and they were treat like a slave has it's written in the bible. The government of egypt treated them and maltreated them as slaves. In egypt they have 10 or 12 God's and Goddesses but there came a time when isrealites need to leave egypt to live in the promised land where they can serve the true God the one and only true God. So God proved within the kingdom of egypt that he's the true God and there is nobody else. When he performed miracles and wonders that the God's of Egypt cannot control. In egypt they have a God which is called the God of denial, when God turned the waters on the nile into blood causing fishes to die, he proved that he is superior that they acknowledge God.
God display his being God being is powerful when he opened the sea where the Egyptians cannot attack the isrealites because they were protected in both sides by the water, at their back a pillar of fire. After they have all cross the Egyptians followed. Psalm 106 chapter 10 says, And he saved them from the hand of him that hated them,and redeemed them from the hand of the enemy. Verse 11 says,And water covered their enemies, there was not one of them left. God has proven himself he the time of the Egyptians dynasty.