The voice of the Lord cries to the city—
and it is sound wisdom to fear your name:
“Hear of the rod and of him who appointed it!
Can I forget any longer the treasures of wickedness in the house of the wicked,
and the scant measure that is accursed?
Shall I acquit the man with wicked scales
and with a bag of deceitful weights?
Your rich men are full of violence;
your inhabitants speak lies,and their tongue is deceitful in their mouth.
Therefore I strike you with a grievous blow,
making you desolate because of your sins.
You shall eat, but not be satisfied,
and there shall be hunger within you;
you shall put away, but not preserve,
and what you preserve I will give to the sword.
You shall sow, but not reap;
you shall tread olives, but not anoint yourselves with oil;
you shall tread grapes, but not drink wine.
For you have kept the statutes of Omri,
and all the works of the house of Ahab;
and you have walked in their counsels,
that I may make you a desolation,
and your inhabitants a hissing;
so you shall bear the scorn of my people.”

via Passage: Micah 6.9-16 ESV Bible Online.

This passage should sound familiar because it reminds us of Leviticus 18.1-4

And the LORD spoke to Moses, saying, “Speak to the people of Israel and say to them, I am the LORD your God. You shall not do as they do in the land of Egypt, where you lived, and you shall not do as they do in the land of Canaan, to which I am bringing you. You shall not walk in their statutes. You shall follow my rules and keep my statutes and walk in them. I am the LORD your God.

Of course, Paul didn’t think the Law was impossible to keep in the sense that it is meant to be kept by God’s people. This was the way that many believers have kept the law. He told children to do it and reminded them of a promised reward.

Thus the Westminster Confession:

Although true believers be not under the law, as a covenant of works [i.e. a demand for personal, perfect, perpetual obedience as a requirement…], to be thereby justified, or condemned; yet is it of great use to them, as well as to others; in that, as a rule of life informing them of the will of God, and their duty, it directs and binds them to walk accordingly; discovering also the sinful pollutions of their nature, hearts, and lives; so as, examining themselves thereby, they may come to further conviction of, humiliation for, and hatred against sin, together with a clearer sight of the need they have of Christ, and the perfection of his obedience. It is likewise of use to the regenerate, to restrain their corruptions, in that it forbids sin: and the threatenings of it serve to show what even their sins deserve; and what afflictions, in this life, they may expect for them, although freed from the curse thereof threatened in the law. The promises of it, in like manner, show them God’s approbation of obedience, and what blessings they may expect upon the performance thereof: although not as due to them by the law as a covenant of works [i.e. a demand for personal, perfect, perpetual obedience as a condition for eternal life]. So as, a man’s doing good, and refraining from evil, because the law encourageth to the one, and deterreth from the other, is no evidence of his being under the law; and, not under grace.

The command to follow God’s law, rather than Ahab’s, Egypt’s, or the laws of the pagan Canaanites, is a command to trust in Jesus as his disciple rather than reject Christ.

See also: Law & Gospel in Presbyterianism