Ezekiel 36 talks about the uncleanness of Israel, not just in the land but in the presence of all the nations to which God had driven them out. This uncleanness is not dirtiness but death, the death of empty idolatry, of exposed flesh, the death that Jesus says comes up from the inside, from the heart, and flows out to defile a person (Mat 15:1-20). They had defiled the land and the name of God, carrying His name in vain, profaning it among the nations. But God says that He will vindicate His holy name by gathering Israel again to her own land, cleansing her from her uncleanness, removing her heart of stone and giving her a new heart, a heart of flesh, and blessing her in the land with abundant fruitfulness. He will vindicate His name by restoring His covenant with His people.
About this new heart, God says, “I will put my Spirit within you, and cause you to walk in my statutes and be careful to obey my rules.” The Word of God had been given to them, and this was their heart: statutes and rules written on stone tablets. But now we have the Word written in human flesh, the very Son of God incarnate, and the Spirit of God indwells us and causes us to walk uprightly. And this is what Paul is addressing in Galatians 3. How can we, who have Christ and His Spirit in us, return to the stone law? How can we expect to merit our own perfection? Can we make this stone heart alive? Life is given in Christ and we receive it through faith. Just as God established His covenant with Abraham, so He establishes His covenant with us through baptism. What was promised to him — that in him all the families of the earth would be blessed — is fulfilled in us. We put on Christ and in Him we are heirs.