1 Thus says the Lord: “For three transgressions of Moab, and for four, I will not revoke the punishment, because he burned to lime the bones of the king of Edom. 2 So I will send a fire upon Moab, and it shall devour the strongholds of Kerioth, and Moab shall die amid uproar, amid shouting and the sound of the trumpet; 3 I will cut off the ruler from its midst, and will kill all its princes with him,” says the Lord.
Interestingly, this oracle of judgment doesn’t concern Israel. Moab’s sin against Edom, which God had already pronounced judgment against earlier, is quite telling. While Israel is usually central to the reason why God judges the surrounding nations, here is one example where God’s judgment comes because of how one pagan nation treats another pagan nation. This highlight the sovereignty of God. Essentially Moab was desecrating graves and using the decomposing corpses to possibly make a whitewashing formula. One commentator quotes:
2:1 Moab’s representative crime neither harmed Israel nor concerned them in any way. Desecration of an Edomite king’s remains was Moab’s sin. Border fortifications between Moab and Edom suggest the probability that the two nations engaged in armed conflict from time to time. Warfare may have been the setting for the Moabite atrocity against the king of Edom.53 Either Edom’s king was burned to death, or his corpse was burned, or his skeletal remains were exhumed and burned to lime. The last suggestion best fits the wording, since the specific reference is to “the bones of Edom’s king.”
Burning the bones to lime suggests total destruction.54 The Targum interpreted the term rendered “as if to lime” to mean that the Moabites used the ashes of the king’s bones in a substance to whitewash houses. The treatment of a human being as mere material was reason enough for Amos’s indictment. Moab’s atrocious act disturbed the Edomite king’s resting place and in Moabite and Edomite thought prevented peace in the afterlife and perhaps even immortality.55 As J. Niehaus explains: “Crimes against humanity bring God’s punishment. This observation is a powerful motivation for God’s people to oppose the mistreatment and neglect of their fellow human beings.”56
Smith, B. K., & Page, F. S. (2001). Vol. 19B: Amos, Obadiah, Jonah (electronic ed.). Logos Library System; The New American Commentary (57–58). Nashville: Broadman & Holman Publishers.
By what standard is God judging one pagan nation’s treatment of another? By His own standard. His law applies to pagan nations, even if they were not the particular recipients’ of such. This is one proof text for Theonomists, those who believe that all nations will be judged by God’s law and must conform to the standards of God’s Law. There are nuanced versions of it, and we are all theonomists in one sense and not in another. Sorting through these distinctions is no easy task.
Should marriage laws, penal codes, etc reflect the Mosaic law word for word? I don’t think so. I would say that the second table of the law, with reference to the horizontal aspects of the law, do apply. I am not for putting to death someone who worships an idol, although I am willing to admit that God will eternally put to death idol worshipers in a more severe judgment than any civil magistrate could dish out. I don’t think the civil magistrate should ordain a particular creed which outlaws those who disagree. Jesus and Paul weren’t expecting this from Rome.
However, Rom. 13 does show that Paul expects the civil magistrate to enforce the second table of the Law, also in 1 Tim speaks of the civil use of the law in restraining evil in society. Paul mentions that they are sword bearers, which does call for capital punishment for certain crimes. He doesn’t elaborate on what crimes are deserving of capital punishment, just mentions that Rome bears the sword as a servant of God.
Romans 13:1–7 (ESV)
1 Let every person be subject to the governing authorities. For there is no authority except from God, and those that exist have been instituted by God. 2 Therefore whoever resists the authorities resists what God has appointed, and those who resist will incur judgment. 3 For rulers are not a terror to good conduct, but to bad. Would you have no fear of the one who is in authority? Then do what is good, and you will receive his approval, 4 for he is God’s servant for your good. But if you do wrong, be afraid, for he does not bear the sword in vain. For he is the servant of God, an avenger who carries out God’s wrath on the wrongdoer. 5 Therefore one must be in subjection, not only to avoid God’s wrath but also for the sake of conscience. 6 For because of this you also pay taxes, for the authorities are ministers of God, attending to this very thing. 7 Pay to all what is owed to them: taxes to whom taxes are owed, revenue to whom revenue is owed, respect to whom respect is owed, honor to whom honor is owed.
1 Timothy 1:8–11 (ESV)
8 Now we know that the law is good, if one uses it lawfully, 9 understanding this, that the law is not laid down for the just but for the lawless and disobedient, for the ungodly and sinners, for the unholy and profane, for those who strike their fathers and mothers, for murderers, 10 the sexually immoral, men who practice homosexuality, enslavers, liars, perjurers, and whatever else is contrary to sound doctrine, 11 in accordance with the gospel of the glory of the blessed God with which I have been entrusted.
This text emphasizes the second table of the law, however makes a brief mention to “sound doctrine” and “gospel”. Does Paul imply that the law of Christ and the Gospel applies to all? Yes and no. God will judge by such a standard, but his emphasis with regards of the law to the “lawless and disobedient”, the “ungodly and sinners”, is really the relationship of the law to the unbelieving society.
Minimally, Paul sees the usefulness of the law in informing the society at large. How far Paul would go with respect to how such law-breaking be penalized is more difficult to answer. He either presumes the Mosaic penal code, or acknowledges some tension of living under Caesar and Christ. I think the later.
At the same time, I would advocate for abolition of slave trade, abortion, weak divorce laws, redefining marriage, among other things, because I truly believe God will not be mocked and will judge us as a people if we act unjustly. Notice that God’s judgment of Moab was based on them acting unjustly, not necessarily for impure worship, etc. God was willing to destroy a nation because of sin and I see no convincing reason why God has ceased from acting as such today.Nations come and go and it is hardly arbitrary in God’s providential rule. If anything, there is an intensifying of God’s dealings with the nations in the New Covenant.
Acts 17:30–31 (ESV)
30 The times of ignorance God overlooked, but now he commands all people everywhere to repent, 31 because he has fixed a day on which he will judge the world in righteousness by a man whom he has appointed; and of this he has given assurance to all by raising him from the dead.”
So what? What are we to do? Jeremiah speaks some practical Godly wisdom to us:
Jeremiah 29:4–7 (ESV)
4 “Thus says the Lord of hosts, the God of Israel, to all the exiles whom I have sent into exile from Jerusalem to Babylon: 5 Build houses and live in them; plant gardens and eat their produce. 6 Take wives and have sons and daughters; take wives for your sons, and give your daughters in marriage, that they may bear sons and daughters; multiply there, and do not decrease. 7 But seek the welfare of the city where I have sent you into exile, and pray to the Lord on its behalf, for in its welfare you will find your welfare.
We are exiles, constantly in exile within the nations of this world, no matter how “Christianized” they may be. We are to seek the welfare of the city in an almost pragmatic fashion, for we know, of all people, that God will destroy a nation for sin. They might think we are as crazy as the one running around saying that the sky is falling, but just smile and retreat. Even Sodom and Gomorrah would have been spared if there were 10 righteous within the city. Let us be concerned about our OWN marriages, our OWN families, our OWN vocations, before we concern ourselves with others. Let us be merciful to the “city” and seek it’s good. This will come through the Gospel. While we should advocate legislation that restrains evil for the justice of all, our main task is to share Christ.
 Smith, B. K., & Page, F. S. (2001). Vol. 19B: Amos, Obadiah, Jonah (electronic ed.). Logos Library System; The New American Commentary (57). Nashville: Broadman & Holman Publishers.