The Bible says over a dozen times that God hardened Pharaoh’s heart so as not to let the Israelites go. The first one comes in Exodus 4:
And the Lord said to Moses, “When you go back to Egypt, see that you do before Pharaoh all the miracles that I have put in your power. But I will harden his heart, so that he will not let the people go. (Exodus 4:12)
This has raised for many readers two questions. First the question of ‘why’ God did this. And secondly ‘how’ God did this.
Why did God do this?
The question of ‘why’ is probably easier to answer first since God himself gives a reason why. This is what God told Moses to say to Pharaoh before the seventh plague, the plague of hail:
13 Then the Lord said to Moses, “Get up early in the morning, confront Pharaoh and say to him, ‘This is what the Lord, the God of the Hebrews, says: Let my people go, so that they may worship me, 14 or this time I will send the full force of my plagues against you and against your officials and your people, so you may know that there is no one like me in all the earth. 15 For by now I could have stretched out my hand and struck you and your people with a plague that would have wiped you off the earth. 16 But I have raised you up for this very purpose, that I might show you my power and that my name might be proclaimed in all the earth. 17 You still set yourself against my people and will not let them go. (Exodus 9:13-17 ESV)
So the answer God gave, in fact the ‘why’ which God instructed Moses is given in verse 16. God put Pharaoh on the throne and brought about the entire situation in order to demonstrate his power to the Egyptians and other Gentile nations. This is consistent with many other passages in Old and New Testament which show that God’s interactions with Israel throughout history (including up to today) are in large part a witness and evidence to all mankind, not intended for Israel alone.
How did God do it?
A superficial reading of “harden his heart” might imply some kind of mind control to some readers, but the context through the twenty-odd references to Pharaoh’s heart during this process in Exodus and in later comment in later Old Testament books, makes it clear that Pharaoh was capable also of hardening his own already hard heart. This was an inclination already present for powerful economic reasons in the Egyptian court.
Look again at Exodus 9:17 above and it is Pharaoh himself who sets himself against God’s people and will not let them go. And we get this repeated statement that Pharaoh hardened his own heart:
But Pharaoh hardened his heart this time also, and did not let the people go. (Exodus 8:32 ESV)
Exodus 8:32 clearly isn’t mind control. In fact mind control is something unknown in the Bible. It is difficult to find any examples of direct action on the mind.
Some writers have cited 1 Samuel 16:14 “Now the spirit of the Lord departed from Saul, and an evil spirit from the Lord tormented him.” as proof that God was affecting Saul’s brain chemistry. Well God is in control of the physical health of all creatures, and there is a chemical component to behaviour. But against that where Saul’s servants said to him, “See now, an evil spirit from God is tormenting you” their comment only indicates the medical understanding of Saul’s servants (possibly Saul’s physician?) around 1000 BC. The most notable thing about Saul’s servants reading, and the 1 Samuel record, is how different this strictly monotheistic approach to illness is from the dualist diagnosis of mental disturbance as due to “demons” current in Jewish medicine during the Greek and Roman eras. The same difference can be seen between Exodus 4:11 where God makes man blind, mute, deaf, and the Pharisee-era synoptic Gospel records where Jewish medicine ascribes blindness, muteness, and deafness to dualistic causes.
So we are left with the “how” defaulting to the explanations running throughout Exodus chapters 7 to 14, of the Egyptians being confirmed in their already predisposed position largely by events and circumstance.
Pharaoh and predestination?
There is another, third, question related to God’s hardening of Pharaoh’s heart that is raised – and dealt with – by Paul in Romans 9. That question is how the purpose of God, as it worked out in Pharaoh’s responses and his death in the Red Sea, was in God’s plan. And Paul raises it as part of a much bigger question relating to God’s choice, and the justice of God’s dealing with mankind.
14 What then shall we say? Is God unjust? Not at all! 15 For he says to Moses,
“I will have mercy on whom I have mercy,
and I will have compassion on whom I have compassion.”
16 It does not, therefore, depend on human desire or effort, but on God’s mercy. 17 For Scripture says to Pharaoh: “I raised you up for this very purpose, that I might display my power in you and that my name might be proclaimed in all the earth.” 18 Therefore God has mercy on whom he wants to have mercy, and he hardens whom he wants to harden. (Romans 9:14-18 ESV)
This has sometimes – particularly by Calvinist writers – been cited as an example of predestination. Although that is evidently not the way that the whole flow of Paul’s argument in Roman’s 9 goes. However this subject deserves more than a footnote here to the original Pharaoh question, so we can leave it with a necessary part of Paul’s answer:
19 One of you will say to me: “Then why does God still blame us? For who is able to resist his will?” 20 But who are you, a human being, to talk back to God? “Shall what is formed say to the one who formed it, ‘Why did you make me like this?’” 21 Does not the potter have the right to make out of the same lump of clay some pottery for special purposes and some for common use? (Romans 9:19-21 ESV)