That the Lord hardened Pharaoh's heart has been a struggle for Christians for a long time. I'm not the first person to wonder whether Pharaoh's free will was violated by God hardening his heart. And, if that's the case, then Pharaoh isn't really responsible for all of his refusals to let the people of Israel go. I think a lot of Christians struggle with this, and they have struggled with it from the beginning of the church.
In Romans Paul addresses this problem directly:
Romans 9:17-24
7For the Scripture says to Pharaoh, "For this very purpose I have raised you up, that I might show my power in you, and that my name might be proclaimed in all the earth." 18So then he has mercy on whomever he wills, and he hardens whomever he wills. 19You will say to me then, "Why does he still find fault? For who can resist his will?" 20But who are you, O man, to answer back to God? Will what is molded say to its molder, "Why have you made me like this?" 21 Has the potter no right over the clay, to make out of the same lump one vessel for honorable use and another for dishonorable use? 22What if God, desiring to show his wrath and to make known his power, has endured with much patience vessels of wrath prepared for destruction, 23in order to make known the riches of his glory for vessels of mercy, which he has prepared beforehand for glory— 24even us whom he has called,not from the Jews only but also from the Gentiles?
The first response that Paul has to the "Pharaoh question" is that you shouldn't really question it. If we have faith in God, then we trust that He obeys His own rules and is consistent in His application of them. I think the second answer that Paul gives, if we read between the lines a little, centers on the eternal nature of God. If God is all-powerful, then he has the power to direct history without violating people's free will. And, since He's all-knowing and exists outside of time, he has the ability to know what people will choose without interfering with their ability to make the choice.
God knew beforehand exactly how the Jews would treat Jesus and that Jesus would be crucified. And, you could say that God's providence placed the Jews of Jesus' time in the right place at the right time with the right attitude for causing His death. Did that make them less responsible for their choice? Absolutely not.
God's hardening of Pharaoh's heart is the same thing. God's providential role in shaping Israel's history is undeniable. Pharaoh is simply one of the devices that God uses to bring about that providence. Does that make Pharaoh less accountable for his decisions? No, it just makes God more magnificent that he can control historical outcomes while still allowing people to make their own choices.
There is at least one practical question that arises when we think about God hardening Pharaoh's heart in the context of Romans. That is, does God know who is going to be saved and who is going to be lost? If we apply the same principle that we learned from Pharaoh, I think the answer must be "yes". But, he knows this without violating our ability to choose salvation. That is the key distinction from those who believe in Predestination. In Predestination God's sovereign will controls exactly who is saved and who is lost. Pharaoh teaches us, however, that while God might know how something is going to turn out and that human history invariably follows God's providence, it is still left up to the individual to choose good or evil. After all, God might know who will be saved and who will be lost, but we don't. So, make choices that lead to salvation.
