The law of God must be in our hearts. When promising the new covenant, God said, "Behold the days are coming when I will make a new covenant... I will put my law within them and on their heart I will write it..."(Jeremiah 31:31-33.cf Romans 2:15).
Why is the heart the place where God’s law must be? Well, that is the place where it will be alongside faith. It is in the heart that man believes in Christ for justification (Romans 10:8-10). Only there, in the heart, alongside faith, will God’s law work for our freedom (Romans 8:1-2).
God justifies and saves those who have in their hearts a love of God’s law alongside a faith in God’s Son.
1 Delight in God’s Law
With God’s law in your heart you will...
love the truth not exchange or reject it (Romans 1:25, 2:8).
prefer God’s truth to man's lies. (Romans 3:4).
delight in God’s law in your inner being (Romans 7:22).
set your mind on the things of the Spirit (Romans 8:5-8).
feel indebted or obligated to keep God’s law as your glad duty (Romans 8:1-2,12-13).
2 Consciousness of Sin
With God’s law in your heart you will...
be led by God’s kindness to repentance (Romans 2:4-5)
not brag about your relationship to God (Romans 2:17).
exclude any boasting about your righteousness (Romans 3:27, 11:18).
become very conscious (not complacent) regarding your sins (Romans 3:20).
say, "But for Christ I am a wretched man!" and rely on Christ for deliverance (Romans 7:24-25).
not lose sight of the severity of God (Romans 11:22).
not think of yourself more highly than you ought (Romans 12:3).
show concern (not contempt) for your weaker brother (Romans 14:10).
3 A Deep Gratitude Toward God
With God’s law in your heart you will...
not show contempt for God’s kindness (Romans l:21, 2:4).
cry out, "Abba, Father!" (Romans 8:15).
share with God’s people in need (Romans 12:13).
4 A Yearning for Eternal Life
With God’s law in your heart you will...
be joyful in trouble (Romans 5:3).
see your troubles as nothing compared to glory (Romans 8:18).
groan inwardly waiting for your hope to be realised (Romans 8:19-25).
persevere prayerfully (Romans 12:12).
5 Your Will Yielded and Obedient
With God’s law in your heart you will...
not let sin reign in your mortal body (Romans 6:12).
offer your body to God as his instrument (Romans 6:13).
obey the form of teaching God’s law provides (Romans 6:17).
become a slave of righteousness (Romans 6:18).
be clay in the hands of the Potter (Romans 9:20 cf Isaiah 45:9).