We will look first at “people hardening their own hearts,” for I believe this happens BEFORE God hardens their hearts. A classic example of someone “hardening their heart” is found in Pharaoh (the “king” of Egypt). When Moses and Aaron approached Pharaoh for the first time, they told him, “Thus says the LORD God of Israel: ‘Let My people go, that they may hold a feast to Me in the wilderness.’ 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’” (NKJV). Pharaoh REFUSED to listen to God’s voice through Moses and with a haughty spirit he REBELLED against the Lord. We know that Moses and Aaron continued to deliver this same message to Pharaoh accompanied by various plagues and yet Pharaoh continued to “harden his heart.” In Exodus 8:15 & 32 we read, “But when Pharaoh saw that there was relief, HE HARDENED HIS HEART AND DID NOT HEED THEM….But Pharaoh HARDENED HIS HEART at this time also; neither would he let the people go.” Again, when people “harden their hearts” they are REJECTING God’s Word and REBELLING against the Lord in open defiance.

Now let’s consider “God hardening Pharaoh’s heart.” Exodus 7:1-4 says, “So the LORD said to Moses: ‘See, I have made you as God to Pharaoh, and Aaron your brother shall be your prophet. You shall speak all that I command you. And Aaron your brother shall speak to Pharaoh to send the children of Israel out of his land. And I WILL HARDEN PHARAOH’S HEART and multiply My signs and wonders in the land of Egypt. But Pharaoh will not heed you, so that I may lay My hand on Egypt and bring My armies and My people, the children of Israel, out of the land of Egypt by great judgments. And the Egyptians shall know that I am the LORD, when I stretch out My hand on Egypt and bring out the children of Israel from among them.’” We saw earlier (in Exodus 5:1-2 and 8:15 & 32) that Pharaoh hardened his heart against the Word of the Lord and refused to let the children of Israel go. Now we see “God hardening Pharaoh’s heart” and thus Pharaoh once again refused to heed God’s Word. Pharaoh’s reaction was the same in both cases; he REFUSED to obey God’s Word by REBELLING against it.

Your question is valid, “What is the difference between Pharaoh hardening his own heart and God hardening his heart? I believe the answer lies in both man’s own FREE WILL and God’s SOVEREIGNTY. Pharaoh acted according to his own free will; he hated God’s Word and God’s people and in rebellion against God he would not let them go. His heart was made up; it was “hard as a rock” and he would not budge. Yet God, in His sovereignty, determined that Pharaoh would reject Him and His word and He would then bring judgments upon the land in order to manifest to the Egyptians that He was the Lord. We see this side of the truth in Romans 9:15-18, “For He says to Moses, ‘I will have mercy on whomever I will have mercy, and I will have compassion on whomever I will have compassion.’ So then it is not of him who wills, nor of him who runs, but of God who shows mercy. For the Scripture says to 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.” God used Pharaoh as an example to others and in order to do this “He hardened his heart.” The real question is, “How EXACTLY did God harden His heart?” Did He make Pharaoh do something against His will? No, we’ve already established the fact that Pharaoh acted according to his own free will. The answer lies in what we saw in verse 18, “Therefore He has mercy on whom He will, and whom He will He hardens.” In a word, if God doesn’t show mercy to someone, their HEARTS REMAIN HARDENED! Another way of looking at this is that God LETS MAN PERSIST IN THEIR REBELLION AGAINST THEM. Instead of humbling them and convicting them by the Holy Spirit, He allows them to reject Him. This is their heart’s desire and He lets them have their own way without any restraint and their hearts become even harder as they hear God’s Word and continue to reject it.

This leads us to your last point concerning “God giving people over to a depraved mind.” You are, no doubt, thinking of Romans 1:28 which states, “And even as they did not like to retain God in their knowledge, God GAVE THEM OVER TO A DEBASED MIND, to do those things which are fitting.” I believe this is yet another example of people “hardening their own hearts” and then “God hardening their hearts” by allowing them to persist in their rebellion against Him.  If you read verses 18-23 you will see that God was trying to speak to men through the light of Creation yet men refused to give heed to this knowledge of God. Like Pharaoh they “rebelled against Him” and instead of seeing God as their Creator and worshiping Him “they became fools, and changed the glory of the incorruptible God into an image made like corruptible man—and birds and four-footed animals and creeping things.” Their hearts were so hardened against Him that “God gave them up to uncleanness…to vile passions…to a debased mind” (verses 24, 26, 28).  He treated them like He did Pharaoh, for instead of showing them mercy (by humbling their hearts and bringing them to repentance), He allowed them to have “their heart’s desire,” which was to reject Him and have their own way. Their own way turned out to be a life of depravity, sinking lower and lower into sin and degradation.  (369.3)  (DO)