There is a moral duty inherent in the law of nature to acknowledge God and to worship Him alone. The first commandment obliges all persons, not just as individuals, but also as families and nations; all people and institutions that God sovereignly reigns over are morally bound to acknowledge and submit to Him, and according to each one’s place and calling, enforce God’s Law. Thomas Sproull (1803-1892) argues:

Covenanting with God is the swearing of an oath of fidelity to him. It is the act of subjects engaging in the most solemn manner to be true to their king. This was the import of the covenant entered into by the kingdom of Judah at the inauguration of Joash: “And Jehoiada made a covenant between the Lord, and the king and the people, that they should be the Lord’s people” (2 Kings 11:17). God’s right to men is not based on any conventional arrangement between him and them. It is original and absolute. “All souls are mine” (Ez. 18:4). “It is he that made us, and not we ourselves, we are his people” (Ps. 100:3). It is however their indispensable duty, as rational and moral creatures, to recognise that relation which by a divine constitution they sustain to their Creator; and to give all the security which he requires, that they will be his true and faithful subjects. It is perfectly reasonable—that intelligent beings governed by moral laws, should give their consent to that constitution under which Infinite Wisdom has placed them, and swear allegiance to the “Lord of the whole earth,” by whom it is administered. There is something analogous to this in the constitution of human governments. Nations usually require an oath of allegiance in order to citizenship. And though the principle has been wickedly misapplied, by requiring of men oaths of fidelity to governments that are not in a state of voluntary subjection to the Lord and his Anointed, yet the fact that they do so, demonstrates that men have naturally, some sense of the duty of covenanting.

The Duty of Social Covenanting Illustrated and Enforced

The fact that Scripture approves of Nebuchadnezzar’s (Dan 3:29) and Darius’ (Ezra 6:11-12) imposition of blasphemy laws and promoting of the worship of the true God demonstrates that the justice and equity of such judicial laws is not particular to Israel as a typological nation, but is common or general in its equity because is grounded in the moral law written on the heart of man (See The Law of Nature and the Civil Enforcement of the First Table). Turretin makes this point clearly:

That what prevails not only among the Jews, but also among the Gentiles (following the light of right reason) is of common right. Thus the Greeks, Romans and others had their own laws in which are many things agreeing with the divine laws (which even a comparison of the Mosaic and Roman law alone, instituted by various persons, teaches).

Institutes of Elenctic Theology, XI.xxvi.3.

However, the New Testament duty of the nations to covenant with Christ does not flow from natural equity per se, but rather from the positive command of the New Covenant administration. Today magistrates have the duty to submit not only to Christ’s rule as He is the eternal Son, sustainer of all creation, but also to Him as Mediator, the risen Lord whom God is in the process of putting “all enemies under His feet” (1 Cor. 15:25; cf. Eph. 1:20-23). The nations are Christ’s “heritage” and obligated to “serve the Lord with fear” and to “kiss the Son” lest He “dash them to pieces like a potter’s vessel” (Ps. 2). “The wicked shall be turned into hell, and all the nations that forget God” (Ps. 9:17). “For the nation and kingdom that will not serve [the Church] shall perish; yea, those nations shall be utterly wasted.” (Is. 60:12).

Is. 60:12 – He showeth that God hath given all power and authority here in earth for the use of his Church, and that they which will not serve and profit the same, shall be destroyed.
Is. 60:13 – There is nothing so excellent which shall not serve the necessity of the Church.
Is. 60:16 – Both high and low shall be ready to help and succor thee.
Is. 60:17 – Thy governors shall love thee, and seek they wealth and prosperity.

Geneva Bible (1599) notes

“At that time his voice shook the earth, but now he has promised, “Yet once more I will shake not only the earth but also the heavens.” This phrase, “Yet once more,” indicates the removal of things that are shaken—that is, things that have been made—in order that the things that cannot be shaken may remain. Therefore let us be grateful for receiving a kingdom that cannot be shaken, and thus let us offer to God acceptable worship, with reverence and awe, for our God is a consuming fire” (Heb. 12:26-29).

A nation could not covenant and join themselves to Israel prior to the coming of the Messiah because the dividing wall had not yet been torn down (Eph. 2:16). But now, in the New Covenant, all authority has been given to Christ and His Church is to “make disciples of all nations” baptizing them and teaching them to obey God’s Law (Matt. 28:18-20). The nations that were once strangers and aliens are now to be grafted in to the covenant of grace and made “fellow citizens with the saints and members of the household of God” (Eph. 2:19).

The whole tenor of the declarations, promises, and predictions of the Old Testament, lead to the conclusion that Christianity shall be owned, countenanced, and supported in a national way. God addresses the nations in a collective capacity, reproves them for their idolatry, and calls them to his worship (Isa. 34:1; 41:1, 21-29). He proposes Christ, as his anointed servant, to them (Isa. 42:1); declares that he has given him the nations for his inheritance, and that he shall inherit them all (Ps. 2:8; 82:8; Isa. 52:15; 55:5). Christ addresses himself, not only to individuals, but to whole islands (Isa. 44:1); nations join themselves to him (Isa. 2:2; Micah 4:1-2; Zech. 2:11; 8:20-22), bless themselves, and glory in him (Jer. 4:2); all nations and dominions serve him (Dan. 7:14, 27). They consecrate all things in them, and employ them in his service (Isa. 60:6-12; Zech. 14:20-21); he owns these nations as his, and blesses them, while he breaks in pieces and wastes others (Ps. 33:12; 145:15; Isa. 19:25; Ps. 2:9, 12; Isa. 60:12). The force of the argument arising from these and similar predictions, is such that Mr. Edward Williams, although an independent, acknowledges that they imply a national profession and establishment of Christianity. In answer to the objection, ” If the above prophecies refer to national conversions, does not that lead to national churches? ” he replies, “That a national establishment, if well ordered, appears more agreeable to the prophetic passages we have been considering than the antipaedobaptist plan; nay, more agreeable to the general tenor of revelation.”

Thomas M’Crie (1772-1835), Brief View of the Evidence for the Exercise of Civil Authority About Religion

Nations now have a duty to subject themselves to Christ’s mediatorial kingdom (Ps. 22:28), establish the Church (Ps. 33:12), and covenant with God to further that kingdom as nursing fathers (Is. 49:23; 60:16). The authority which God has given Christ mediatorially includes every nation of the world, and hence prior to His return every nation of the earth must have been brought under that authority by covenanting with Christ. Since we have not yet fully seen this in the course of history we expect a revival of religion and nations actually bowing the knee to Christ prior to His return as the Scriptures plainly indicate.

He is made “heir of all things” (Heb. i. 2) as Mediator, for the heathen and all the ends of the earth are given him for an inheritance, Psal. ii. 8; but that is only church-wise; he shall have a catholic church fathered out of all nations, and all kings, and people, and tongues, and languages shall be made to serve him.

George Gillespie, Aaron’s Rod Blossoming, pg. 94.

“All nations whom thou mad’st shall come
and worship rev’rently
Before thy face; and they, O Lord,
thy name shall glorify.” (Ps. 86:9, SMV)

“All the ends of the world shall remember and turn unto the Lord: and all the kindreds of the nations shall worship before thee. For the kingdom is the Lord‘s: and he is the governor among the nations.” (Ps. 22:27-28)

“Of the increase of his government and peace there shall be no end, upon the throne of David, and upon his kingdom, to order it, and to establish it with judgment and with justice from henceforth even for ever. The zeal of the Lord of hosts will perform this.” (Is. 9:7)

“For the earth shall be filled with the knowledge of the glory of the Lord, as the waters cover the sea.” (Hab. 2:14)

“For from the rising of the sun even unto the going down of the same my name shall be great among the Gentiles; and in every place incense shall be offered unto my name, and a pure offering: for my name shall be great among the heathen, saith the Lord of hosts.” (Mal. 1:11)

“The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever.” (Rev. 11:15; cf. Dan. 7:17)

Samuel Rutherford writes in rebuttal to the Anabaptist notion that covenanting is not necessary:

To lay bands of promises and oaths upon a back-sliding heart, is commanded in the third Command, and is not Judaical, Gen. 14. 22. Gen. 28. 20. Psal. 132. 2. Psal. 76. 11. Its prophesied as a moral duty of Egypt converted under the New Testament, Isa. 19. 21. They shall vow a vow to the Lord, all the Gospel purposes and resolutions spoken to the Lord in praying, in suiting grace to do duties, confessing sins are so many Gospel vows laid upon the heart, to do such duties: nor is there a formal [i.e. the words are not prescribed] swearing required in vows made to God. And this is sinful omission of a morally obliging duty, and morally obliging one man: so it obligeth a Nation, as affirmative precepts do: and this smells of Anabaptism to cry down all Gospel-vows.

A Survey of the Survey of that Summe of Church Discipline, pg. 482.

Fisher’s Catechism, written as an exposition of the Westminster Shorter Catechism, explains the nature of personal and social vows, and national covenanting as a social vow, under the duties of the third commandment:

“Come, and let us join ourselves to the Lord in a perpetual Covenant that shall not be forgotten.” (Jer. 50:5)

“Take away the wicked from before the king, and his throne shall be established in righteousness.” (Prov. 25:5)

“And all Judah rejoiced at the oath; for they had sworn with all their heart.” (2 Chr. 15:15)

“Though it be but a man’s covenant, yet if it be confirmed by an oath, no man disannulleth or addeth thereto.” (Gal. 3:15)