I will give you a new heart and put a new spirit within you; I will take the heart of stone out of your flesh and give you a heart of flesh. (Eze_36:26)
To live in obedience to the will of God, man needs more than his own best efforts and intentions. The history of Israel emphatically demonstrates this. God gave His law. He commanded them, saying, “Walk in My statutes, keep My judgments, and do them" (Eze_20:19). Israel had promised to obey. "All that the LORD has said we will do, and be obedient" (Exo_24:7). Nevertheless, they failed miserably. "Notwithstanding, the children rebelled against Me; they did not walk in My statutes, and were not careful to observe My judgments" (Eze_20:21).
In order to live obedient lives, people need a new life from God, followed by understanding in how to develop that new life. Here, we see a promise from God to supply that new life. "I will give you a new heart and put a new spirit within you." These promises are related to the new covenant of grace that the prophets proclaimed for Israel some day. "Behold, the days are coming . . . when I will make a new covenant with the house of Israel . . . not according to the covenant that I made with their fathers in the day that I took them by the hand to bring them out of the land of Egypt" (Jer_31:31-32). The book of Hebrews elaborates on this new covenant of grace and applies it to the church today: "Therefore, brethren, having boldness to enter the Holiest by the blood of Jesus, by a new and living way which He consecrated for us" (Heb_10:19-20).
When anyone embraces the grace of God offered in Jesus Christ (the mediator, the great High Priest of the new covenant), that person is born again by the Spirit of God. "That which is born of the flesh is flesh, and that which is born of the Spirit is spirit" (Joh_3:6). This is a necessity. "Unless one is born again, he cannot see the kingdom of God" (Joh_3:3). Human "flesh-birth" brings with it a hard spiritual heart (a dead spirit). Spiritual new birth from God replaces this hard heart (this dead, non-responsive spirit). "I will give you a new heart and put a new spirit within you."
Think of our desperate need for this work of God that brings us a new heart, a new life. Those not born again are described as living "in the futility of their mind, having their understanding darkened, being alienated from the life of God . . . because of the hardening of their heart" (Eph_4:17-18). Yet, whoever relies upon the grace of God offered in Jesus Christ becomes a newborn child of God. "Therefore, if anyone is in Christ, he is a new creation; old things have passed away; behold, all things have become new" (2Co_5:17).