God permitted the conflict between Moses and Pharaoh for three reasons at least.
1. In this conflict God displayed His superior power and sovereignty over Pharaoh and the gods of Egypt.
2. God strengthened the faith of His people so that they would trust and obey Him and thereby realize all of His gracious purposes for them as a nation.
3. God also used these events to heighten anticipation of and appreciation for the redemption He would provide. The Israelites would forever after look back on the Exodus as the greatest demonstration of God's love at work for them.
"It is impossible to find a more exact illustration of the truth of Rom. i. than that presented in this story of Pharaoh's conflict with Jehovah."99