The apostle Paul explicitly states that God hardened Pharaoh’s heart (Romans 9:17–18). That, of course, begs the question: If God determined to harden Pharaoh’s heart, then how is God just in holding Pharaoh morally responsible for his sins?
First, though God promised Moses that he would harden Pharaoh’s heart (Exodus 4:21; 7:3), the Exodus account underscores the fact that Pharaoh was responsible for hardening his own heart (Exodus 7:13, 22; 8:15, 19, 32; 9:7; cf. 9:34).
Furthermore, far from hardening Pharaoh’s heart in a direct or deterministic fashion, God presented Pharaoh with ample opportunity to either repent or continue in rebellion. Every time God showed Pharaoh mercy and removed a plague from Egypt, Pharaoh responded in stubborn disobedience. As such, God’s mercy was the occasion for the hardening of Pharaoh’s heart.
Finally, in dealing with this issue, the apostle Paul begins with the presupposition that God judges all men justly (Romans 3:5–8). He emphasizes the fact that people like Pharaoh are “prepared for destruction” because that is ultimately what they will. Every time God provides an opportunity to repent, like Pharaoh they harden their hearts in disobedience and unbelief.
For further study, see Paul Marston and Roger Forster, God’s Strategy in Human History,2nd ed. (Wipf and Stock Publishers, 2000).
“When Pharaoh saw that the rain and hail and
thunder had stopped, he sinned again: He and his
officials hardened their hearts. So Pharaoh’s heart was
hard and he would not let the Israelites go, just as
the LORD had said through Moses.”