Why does God harden hearts?

Most people meet this question in Exodus, and they meet it as an accusation. God is about to send Moses back into Egypt, and before a single plague has fallen, before Pharaoh has said one word, God says this:

Exodus 4:21 (NKJV)

And the LORD said to Moses, “When you go back to Egypt, see that you do all those wonders before Pharaoh which I have put in your hand. But I will harden his heart, so that he will not let the people go.”

If we look at the entire book of Exodus and not simply this verse in isolation, we will see two very prominent things. Ten times we are told that God hardened Pharaoh's heart (4:21; 7:3; 9:12; 10:1, 20, 27; 11:10; 14:4, 8, 17). Ten times we are told that Pharaoh hardened his own (7:13–14, 22; 8:15, 19, 32; 9:7, 34–35; 13:15).

Exodus 8:32 (NKJV)

But Pharaoh hardened his heart at this time also; neither would he let the people go.

Notice that the writer of Exodus is not troubled by this. He is not trying to reconcile the two, or slip one past us while we are looking at the other. He sets them side by side, because both are true.

God did not make a good man wicked

God did not reach into a tender heart and turn it to stone. He did not pour cruelty into a man who had none. Look at Pharaoh before any hardening is mentioned in the story. Moses comes with the word of the LORD, and this is the answer he gets:

Exodus 5:2 (NKJV)

And Pharaoh said, “Who is the LORD, that I should obey His voice to let Israel go? I do not know the LORD, nor will I let Israel go.”

That is not a man who needed corrupting. That is a slave-master who had built his throne on the backs of a whole nation, who had ordered Hebrew boys drowned in the river, and whose settled conviction was that no one in heaven or earth outranked him. When the plagues came, Pharaoh did not do anything he did not want to do. He was never dragged. He was never overruled. At every point he did precisely what he most wanted, and what he most wanted was his own way.

This is how Scripture speaks of hardening in one simple sense — God letting go. Three times in Romans 1, Paul describes God's judgment on a world that will not have Him, and each time the verb is the same: God gave them up. He gave them up to their uncleanness, to their passions, to a debased mind — that is, He handed them over to themselves. He stopped holding them back. And when God stops holding a man back, that man does not become someone else. He becomes, at last, entirely himself.

That is the first half of the answer. Every restraint Pharaoh ever felt — every twinge of conscience, every hesitation, every moment when he nearly relented — was God's mercy holding him in check. When God withdrew that mercy, He did not add one grain of wickedness to Pharaoh's heart. He simply took His hand off a man who had spent his life straining against it.

But God meant it, and He said so in advance

Now we must be honest about the part that is harder to swallow, because a great many writers stop at the paragraph above and leave the reader with the impression that God merely stood by. He did not merely stand by. He announced the hardening before it happened (4:21), and He tells us plainly what He was doing it for:

Exodus 14:4 (NKJV)

“Then I will harden Pharaoh's heart, so that he will pursue them; and I will gain honor over Pharaoh and over all his army, that the Egyptians may know that I am the LORD.” And they did so.

There is the why, and Paul repeats it centuries later, quoting God's own words to Pharaoh as the settled explanation of the whole affair:

Romans 9:17–18 (NKJV)

For the Scripture says to the Pharaoh, “For this very purpose I have raised you up, that I may show My power in you, and that My name may be declared in all the earth.” Therefore He has mercy on whom He wills, and whom He wills He hardens.

So the answer to the question is this: God hardens hearts in order to display His power and make His name known in all the earth. Pharaoh's hardness was not an obstacle God had to work around; it was the very thing through which God worked.

Every refusal set up another plague. Every plague brought down another Egyptian god — the Nile, the sun, the cattle, the firstborn heir — until the greatest empire on earth had been dismantled in public by the God of a slave people. Had Pharaoh let Israel go after the first plague, there would have been no Red Sea. There would have been no song on the far shore. There would have been no story for Israel to tell its children for the next three thousand years.

Why could Pharaoh watch the Nile turn to blood and still say no?

People often ask how any man could see the miracles Pharaoh saw and refuse to bend. But that assumes evidence softens hearts. It does not. Pharaoh had made up his mind before the first plague fell — I do not know the LORD, nor will I let Israel go — and a made-up mind is not moved by facts. It is only confirmed by them.

Do not mistake what happened after the last plague. Pharaoh did not repent when his son died. He surrendered, which is not the same thing, and within days he had changed his mind again and was chasing Israel across the desert with six hundred chariots. Catastrophe did not melt that heart. It only revealed how cold it had gone. This is what hardening does.

The Bible asks the same of us today

Hebrews 3:15 (NKJV)

while it is said: “Today, if you will hear His voice, do not harden your hearts as in the rebellion.”

Today. The warning is not aimed at Egyptians three thousand years ago. It is aimed at the reader, and its urgency comes from the fact that hardening is progressive. Every time God's voice is heard and set aside, the ear grows a little duller. No one chooses, on a particular morning, to become a man who cannot repent. He simply says “not yet” often enough, and one day finds that “not yet” has become “cannot.”

And here we must be careful, because the natural thing to say next is: so soften your heart. But that is precisely what a heart of stone cannot do. Stone does not decide to become flesh. If Pharaoh's own strength could not save him, ours will not save us either; and if the softening of a heart were finally our work, then Hebrews would be handing us an instruction we have no power to carry out.

So God does not hand us an instruction. He makes a promise:

Ezekiel 36:26 (NKJV)

I will give you a new heart and put a new spirit within you; I will take the heart of stone out of your flesh and give you a heart of flesh.

Read who is doing the work in that verse. I will give. I will put. I will take out. Every verb belongs to God. The same sovereign hand that withdrew from Pharaoh and left him to himself is the hand that reaches into a dead man's chest and puts a living heart there — and it is not owed to anyone. It is mercy, and mercy by definition is never earned.