When Jeremiah wrote of the law written on people’s hearts, it is doubtful that he knew what He was saying. His words were spoken in the mindset of the Ten Commandments, which at best were a rudimentary depiction of righteousness and a muted degree of life that fitted the age of the knowledge of good and evil, rather than the coming age of God incarnated in people.
Jesus, manifesting as you is a radical grace that some would rather disbelieve and trust themselves to the parody of righteousness and grace they have made for themselves out of their contractual, self-made law. Sometimes such people have been schooled in a theology that is not the theology of the Christian Church.
When Jesus referred to the Jews and ‘their law’ He was referring to the selective bits of law people make for themselves and then go on to foster the illusion that they keep the law because they have seized on some cultural icon from which to make a denomination.
The coolness of what God has in mind was difficult enough to understand then, just as it is now when people go into reductionist mode and reduce life to law and rules because they resist coming to terms with the incarnation as Christ our life.
The illusion of the law and its tenets is that it appears to have substance. The truth that is Christ our life is that only life in the Spirit has substance because it is this life of Christ that comes in the flesh to be expressed as you and I. So the law written on human hearts in fact refers to Christ in us.
The Son of God was incarnated firstly as Jesus of Nazareth. The Son of God was incarnated in you following the atonement as Jesus come in our flesh. This was the declaration of Pentecost. To restrict Pentecost to gifts and signs is to miss the point. Pentecost signalled the start of the incarnation of Christ in us.
Martin Davis writes, “
Jesus was conceived by the Holy Spirit. Therefore, he is the “Son of God.” Jesus was born of the Virgin Mary. Therefore, he is the “son of Mary,” that is, he is a human being. Jesus is the one person in all human history who is both fully God and fully human! The birth of Jesus fulfilled the prophecy of Isaiah, which told of a child born of a virgin, who would be called “Immanuel,” which means “God with us” (Isaiah 7:14; Matthew 1:23).” (1)
The exquisite joining of ourselves to God takes place in the person of Jesus. In Jesus Christ we are joined to God and God is joined to us. We are joined by God to God in Jesus Christ who joins humanity to the trinity in Himself. Hopefully we can see how talk of the law is irrelevant and misses the Great Truth of our achieved union with God in Jesus Christ.
(1) Davis, Martin M.. The Christian Doctrine of God . AsiAfrica Ministries, Inc.. Kindle Edition.