When it comes to the hard of heart, my previous Bible study had left me with the impression that this was relegated to the example of Pharaoh’s heart, and the Lord’s sovereign dealing within it (roughly throughout Exodus 4-14). It was this example that Paul plucked from Exodus to make his point concerning the effectiveness, sovereignty, justice and mercy of God in salvation (Romans 9). But as when one walks through a vineyard and finds that the farther he goes the more he is privileged to pick, eat and be satisfied, so it is with one’s walk and gleanings through the Bible. And thus,
the last gleaning dealt with the hardness of Israel’s heart – that which the Lord required, and that which only the Lord can give, Israel did not have but was no less called to have it (see Deuteronomy 10, 29).
In the book of Joshua, the Lord hardens the hearts of the enemies of Israel so that they will come into battle against the Lord and be completely cut off from the earth, disinherited that God’s people might rest in the new Eden (which never materialized and thus purposed to look forward to something greater, namely, Christ, and through Him, the hope of an eternal and new heaven and earth), see Joshua 11:20. Here also the hardening of their hearts is equated to receiving no mercy from God or the people of Israel in battle. The hard of heart receive justice only.
We see this previously in Deuteronomy 2:30 with Sihon the King of Heshbon. The Lord made his spirit hard and his heart obstinate in order that he might fight with Israel and be destroyed.
We see this prior to this in Exodus 14:17 when the Lord hardens the hearts of not one person, but thousands of Egyptians which leads to their destruction in the Sea.
Here is the point: Be not hard of heart! And do not say to yourselves, “Well who can resist his will,” as they did to Paul in Romans 9, for Paul has already provided any adequate answer. Suffice it to say that Pharaoh, the enemies of Israel, Sihon, the company of Egyptians, and apparently the majority of ancient Israel, were not doing anything that they did not previously desire to do or would have done, and thus they are responsible. And yet there is a time in which the Lord also makes the heart obstinate. This is balanced by the following: that while the Lord hardens hearts, and is just in doing so, you are no less responsible to respond in saving faith to His overtures which require new hearts. The fact that you live this day should cause you to cast yourself wholeheartedly upon his mercy, and the grace revealed to us in Jesus Christ, in whom a new heart for sinners is promised! If you do not, the destruction is yours to own, and be do not be fooled, the hard of heart are hardened unto destruction. Therefore, be not hard of heart! God has promised in the New Covenant that He will give a new heart, and that Covenant has been ratified by the blood of Christ – it is offered to you today in Christ! Repent and believe upon Jesus, and God will save you, and be for you!