What happened to Pharaoh as he kept opposing God?
As Pharaoh repeatedly opposed God, the weight of God's wrath pressed down on him more heavily, and he was hardened. Scripture says God hardened him, yet he hardened his own heart by rejecting God's place of choice, not because God forced him to do it.
Les teaches that the word "hardeneth" in Scripture is usually translated "heavy," similar to Isaiah's burden. The more Pharaoh tried to oppose God, the more the weight of God's wrath weighed down on him. Les explains that Pharaoh, like anyone today, came to a place of hardening his own heart, not because God made him do it, but because God placed him in a position of either accepting or rejecting, and by rejecting he hardened his own heart. Even though Scripture says God hardened, the principle is: men are not lost because they are hardened; they are hardened because they are lost.
Therefore hath he mercy on whom he will have mercy, and whom he will he hardeneth.