The Bible says:"To day if ye will hear his voice, harden not your hearts." Hebrews 4:7. But in the Old Testament we read of how God Himself hardened the heart of Pharaoh when it came to letting the Israelites leave Egypt. (We read the story of Pharaoh beginning in Exodus 5, and onward.)
Now at a first glance that seems like a complete contradiction between the Old and the New Testament, but, when we take a closer look we can the see just how merciful, loving and patient God really is.
You see, God in His lovingkindness wants to draw ALL men unto Him, (John 12:32) and that is exactly what He was trying to do in the case of Pharaoh. God hardened the Pharaoh's heart only on the matter of letting God's people go; God did not harden his heart to keep him from repenting. Do you see the difference?
God wanted the Pharaoh to repent and turn his life over to God, but he would not, and so God hardened his heart when it came to letting the people go; thus God had reason to send the plagues in order that the Pharaoh might see more miracles and repent towards God.
But the Pharaoh would not repent, and so God continued to harden his heart in the sense that he would not let the Israelites go.
Now we all know that God is all-knowing and knew very well that no matter how many plagues He would send upon the Egyptians that the Pharaoh would not repent. So why did He continue to send the plagues and make all of Egypt suffer just because the Pharaoh would not repent?
God uses the wicked to show His power to the righteous. What the Israelites experienced from the plagues no doubt was to help them in the wilderness. God showed His power to them through the plagues, and that He was their God and that He would protect them in every situation.
The Bible doesn't say, but perhaps there were Egyptians who also believed as a result of the plagues. Perhaps they never came forward, but rather believed in their hearts.
But most importantly, I believe it is for a parable to show us just how loving and patient God really is. He knocks on the hearts of sinners and gives them numerous chances to repent. Not only does He give them these chances but God sets these circumstances up so that they will see the truth and repent.
We can clearly see, that God did not want to give up on Pharaoh, but at last He did. When Pharaoh meets God face to face on the other side, he will have no excuse for his unrepentant heart.
In the same way every sinner who finds himself/herself thrown into hell on the other side will have no excuse because God will have given them every opportunity to repent; but they would not.
"The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance." 2 Peter 3:9.
So when you find yourself in a tough situation, ask yourself if there is a sin that you have not yet repented of. If God brings one to mind, repent immediately. If He does not bring any sin to mind, then perhaps the reason you are in this tough spot is because God is strengthening your spiritual muscles.