Why did Christ rebuke Nicodemus for not understanding the nature of man and the need of regeneration, given that he was a teacher of the law? What does the Old Testament Scriptures teach about these things?

“He has shown you, O man, what is good; and what does the LORD require of you, but to do justly, to love mercy, and to walk humbly with your God? [Micah 6:8]

The prophet Micah refers to the second tablet of the Law as what is good. It defines how we should love our neighbor by putting content to the word love. True religion is to observe what is good toward all men and to take pleasure in kindness. True religion is marked by humility and by delighting in mercy.

The man who understands mercy is the man David calls blessed, “Blessed is the man whose sin is covered…and in whose spirit there is no deceit.” [Psalm 32] This man has lost his pride in his experience of the mercy of God, and therefore he is able to extend mercy toward others.

Micah and David give us a sense that true religion is of the heart. This agrees with the wise man who says, “Out of the heart come the issues of life” [Proverbs 4:23] and again, “As a man thinks so is he.” [Proverbs 23:7]

The condition of man after the Fall is graphically illustrated in the Genesis Flood account. “The wickedness of man was great in the earth, and every intent of the thoughts of his heart was only evil continually." [Genesis 6:5]

The idea of this heart condition affecting the covenant people is taught by Moses. “Circumcise the foreskin of your heart…” [Deuteronomy 10:16] Circumcision applied to the heart teaches us that the physical covenant sign given to Abraham carries a spiritual meaning pointing to a spiritual covenant.

The prophet Jeremiah agrees with Moses about the heart condition of man, “The heart is deceitful about all things and desperately wicked, who can know it?” [Jeremiah 17:9] Jeremiah uses the same language as Moses, “Circumcise the foreskin of your heart...” [Jeremiah 4:4] Then Jeremiah introduces the New Covenant and gives us the great promise, “I will write My Law on their heart...” [Jeremiah 31]

Moses had prophesied that God will circumcise the heart after Israel returns from captivity, “And the LORD your God will circumcise your heart and the heart of your descendants, to love the LORD your God with all your heart and with all your soul, that you may live." [Deuteronomy 30:6] Moses links the ideas of circumcising the heart with the Law, since the Law defines how we are to love God.

The prophet Ezekiel compares the new heart to flesh and the old heart to stone, “I will give them one heart, and I will put a new spirit within them, and take the stony heart out of their flesh, and give them a heart of flesh…” [Ezekiel 11:19 & 36:26]

The Old Testament presents us with our fatal heart condition, but promises that God will circumcise the heart of His people by writing His Law on the new heart. The New Covenant is contrasted with the Old Covenant in that the Law is to be written on the heart of all the covenant people rather than on tablets of stone.

We refer to Isaiah as the gospel prophet because he answers the vital questions surrounding the messenger of the covenant; the Holy One of Israel who would seal the covenant with His own blood. “Surely He has borne our griefs and carried our sorrows; yet we esteemed Him stricken, smitten by God, and afflicted. But He was wounded for our transgressions, He was bruised for our iniquities; the chastisement for our peace was upon Him, and by His stripes we are healed.” [Isaiah 53]

We can sympathize with Nicodemus because he lived in the Old Covenant. The modern day Nicodemus on this side of the cross is harder to understand, except to say that regeneration is still required before a man can see and enter into the kingdom of God. [John 3]

Without regeneration a religious man will pursue his own righteousness by the works of the law or by a life of morality. He hopes his good works will out number his sins. This he thinks will insure his acceptance with God. Again, they have not listened to the gospel prophet, “We are all like an unclean thing, and all our righteousnesses are like filthy rags…” [Isaiah 64:6]

Early in Genesis God revealed the way of righteousness. Abraham is our example of how a man is made right before God. “Abraham believed God, and it was counted to him as righteousness.” [Genesis 15:6]

The doctrine of justification by faith alone in Christ alone has to do with the supernatural process of regeneration whereby a man is born again; that is, born of the Spirit and declared righteous before God because he is covered in the perfect righteousness of Jesus Christ.

The covenant making God of Abraham, Isaac and Jacob is the One who makes men to differ according to His good pleasure. He is the potter; we are the clay. [Isaiah 29:16] We invite men to come to Christ knowing that he has redeemed a multiple that no man can number from all nations and all generations. He has fulfilled the covenant and is now gathering His people. “Look now toward heaven, and count the stars if you are able to number them…So shall your descendants be.” [Genesis 15:5]