Question: Exodus 10:1 says that the Lord hardened Pharaoh's heart, but Exodus 8:15 says Pharaoh hardened his heart. Who hardened his heart?
Answer: The same sun that hardens the clay also melts the wax. The clay responds to the sun by hardening, while the wax responds by softening. It's the condition of the heart that determines whether or not it hardens or softens.
Hebrews 4:7 says, "Today if you hear His voice, do not harden your hearts." When God speaks to us and we obey Him, our heart remains soft. However, each time He speaks and we refuse to listen, our hearts get harder. When God spoke to Pharaoh and he refused to yield, his heart became hard.
Suppose you told an atheist, "Jesus loves you." The atheist responds, "You make me so mad!" Who mad him mad? In one sense, you did-by speaking words he didn't want to hear. In another sense, he made himself mad-by resisting the message. In the same way, the Lord hardened Pharaoh's heart by speaking words he didn't want to hear, and Pharaoh hardened his own heart by resisting the message.
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