The doctrine of the two kingdoms is often confused as a distinction between church and state, but this is not the case. While Christ’s reign over all things in power and over His church in grace do indeed relate to the institutions of the church and the civil magistracy, the kingdom of power is not itself a reference to the institution of the civil magistrate. The civil magistrate finds its origin in the secondary laws of nature arising out of the fifth commandment, while the church finds its origin in the positive institution of the Mediator in the covenant of grace.

…a twofold kingdom of Jesus Christ: one, as he is the eternal Son of God, reigning together with the Father and the Holy Ghost overall things; and so the magistrate is his vicegerent, and holds his office of and under him; another, as Mediator and Head of the church, and so the magistrate doth not hold his office of and under Christ as his vicegerent.

George Gillespie, Aaron’s Rod Blossoming, pg. 90.

Reformed Theology historically has understood that Christ has two kingdoms, the kingdom of His power (regnum potentiae) and the kingdom of grace (regnum gratiae), not as disparate reigns but as distinctions in the manner and exercise of His rule.  Christ’s kingdom of power is His government of all things in providence which are “his most holy, wise, and powerful preserving, and governing all his creatures; ordering them, and all their actions, to his own glory” (WLC 18). The kingdom of grace is Christ’s special, mediatorial rule over His Church. “As God he needed not receive a kingdom, but as mediator his Father gifted him with a kingdom to him and all his heirs” (Rutherford’s Catechism, pg. 37).

Sometimes a third kingdom is identified, the kingdom of glory (regnum gloriae). However, the kingdom of glory is essentially the kingdom of grace consummated (Matt. 25:34), which will take place at His second coming; “the kingdom of glory may be hastened” (WSC 102) compared with “hasten the time of his second coming, and our reigning with him for ever” (WLC 191). The kingdoms of grace and glory “are not so much different kingdoms, as different states in the same kingdom: according to the common maxim, Grace is glory begun, and glory is grace consummated, or in perfection” (Fisher’s Catechism, Second Petition, Q. 13).

The Kingdom of Grace

Yet have I set my king upon my holy hill of Zion (Ps. 2:6); And he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end (Luke 1:33); he that is holy, he that is true, he that hath the key of David, he that openeth, and no man shutteth; and shutteth, and no man openeth (Rev. 3:7; cf. Is. 22:22); Thy kingdom come, Thy will be done in earth, as it is in heaven (Matt. 6:10).

The Westminster Larger Catechism goes into more detail about what the kingdom of grace is, and how we ought to pray for its advance:

Q. 191. What do we pray for in the second petition?
A. In the second petition, (which is, Thy Kingdom come,) acknowledging ourselves and all mankind to be by nature under the dominion of sin and Satan, we pray that the kingdom of sin and Satan may be destroyed, the gospel propagated throughout the world, the Jews called, the fullness of the Gentiles brought in; the church furnished with all gospel officers and ordinances, purged from corruption, countenanced and maintained by the civil magistrates; that the ordinances of Christ may be purely dispensed, and made effectual to the converting of those that are yet in their sins, and the confirming, comforting, and building up those that are already converted: that Christ would rule in our hearts here, and hasten the time of his second coming, and our reigning with him for ever: and that he would be pleased so to exercise the kingdom of his power in all the world, as may best conduce to these ends.

Westminster Larger Catechism, 191.

So we see that Christ rules His kingdom of grace not only spiritually as Lord and Savior of the elect, but also in the ordinances, worship, and government that He has instituted for the visible church, “giving them officers, laws, and censures, by which he visibly governs them” (WLC 45); “The visible Church…is the kingdom of the Lord Jesus Christ” (WCF 25:2). The distinction between the visible and the invisible church is one which lies within the context of the kingdom of grace; it may be viewed “either as to outward dispensation, or inward operation” (Fisher’s Catechism, Second Petition, Q. 14). At the second coming the kingdom of grace/glory will come to an end as Christ delivers the kingdom back to the Father: “Then cometh the end, when he shall have delivered up the kingdom to God, even the Father; when he shall have put down all rule and all authority and power” (1 Cor. 15:24).

Nothing can stop the gospel and expansion of the Church, “upon this rock I will build my church; and the gates of hell shall not prevail against it” (Matt. 16:18); the salvation of the Jews, “And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob: For this is my covenant unto them, when I shall take away their sins“ (Rom. 11:26-27); the fullness of the Gentiles, “And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world. Amen.” (Matt. 28:18-20); and the destruction of sin and Satan, “Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ: for the accuser of our brethren is cast down, which accused them before our God day and night. And they overcame him by the blood of the Lamb, and by the word of their testimony; and they loved not their lives unto the death” (Rev. 12:10-11).

Many people are deceived into thinking that the general progress of human civilization, general education and culture, science and invention, and economic and social progress and organization can restrain or destroy Satan’s kingdom. All these things can fit in with Satan’s kingdom as much as with God’s kingdom. Only the gospel of Christ, by the power of the Holy Spirit, really destroys Satan’s kingdom.

J.G. Vos, Commentary on WLC 191, pg. 551.

The gospel of Christ, by the power of the Holy Spirit, advances through the visible Church. As churches are planted and the gospel is preached, as the sacraments are rightly administered and the public and private worship of God is kept pure, as heresy and unrepentant sin are disciplined according to the government that Christ has established, and as Christ is submitted to in all things as Head of the Church, His kingdom advances. The Directory for the Publick Worship of God admonishes us to pray particularly “for that church and kingdom whereof we are members, that therein God would establish peace and truth, the purity of all his ordinances, and the power of godliness; prevent and remove heresy, schism, profaneness, superstition, security, and unfruitfulness under the means of grace; heal all our rents and divisions, and preserve us from breach of our Solemn Covenant.”

The Kingdom of Power

For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether they be thrones, or dominions, or principalities, or powers: all things were created by him, and for him: And he is before all things, and by him all things consist (Col. 1:16-17).

Q. What is Christ’s kingdom of power?

A. The hand of Christ’s power coming in and bearing up the whole frame of nature tottering and like to fall to nothing through Adam’s sin (Col. 1:17; Heb. 1:2).

Rutherford’s Catechism, pg. 37

Contrary to the common notion that Christ rules only over the Church, John Owen explains:

Some seem to imagine, that the kingly power of Christ towards the church consists only in external rule by the Gospel and the laws thereof, requiring obedience unto the officers and rulers that he hath appointed therein. It is true, that this also belongs unto his kingly power and rule; but to suppose that it consisteth solely therein, is an ebullition from the poisonous fountain of the denial of his divine person. For if he be not God over all, whatever in words may be pretended or ascribed unto him, he is capable of no other rule or power. But indeed no one act of his kingly office can be aright conceived or acknowledged, without a respect had unto his divine person…

For this power over the whole creation is not only a moral right to rule and govern it; but it is also accompanied with virtue, force, or almighty power, to act, order, and dispose of it at his pleasure. So is it described by the apostle from the Psalmist, Heb. i. 10–12, “Thou, Lord, in the beginning hast laid the foundation of the earth; and the heavens are the works of thine hands: they shall perish, but thou remainest; and they all shall wax old as doth a garment; and as a vesture shalt thou fold them up, and they shall be changed: but thou art the same, and thy years shall not fail.”

Christologia, ch. vii.

Christ, as the eternal Son of God and Creator of all things, has always been “upholding all things by the word of his power” (Heb. 1:3), “none can stay his hand, or say unto him, What doest thou?” (Dan. 4:35). He has foreordained whatsoever comes to pass and has absolute authority and control over even the most insignificant and, humanly speaking, random events: “The lot is cast into the lap; but the whole disposing thereof is of the Lord” (Ps. 16:33). 

There is some debate over how to speak of Christ as ruling and reigning as He is the eternal Son of God only or if He also rules the kingdom of power as Mediator. Earlier writers, largely due to the threat of Erastianism, would rather refer to His rule and reign over all things (kingdom of power) only as He is God and not as He is the Mediator. However, all agree that the rule and reign of the Son of God over all things (kingdom of power) serves the good of His rule and reign over His church (kingdom of grace). Christ uses the kingdom of His power to providentially expand His kingdom of grace. His being given to rule over nations (Ps. 2) shows that nations as nations will be joined to the visible church (Ps. 22:27-28) just as families as families are joined to the visible church (Gen. 18:19; Acts 16:31) without changing the nature of Christ’s rule.

After explaining the details of the kingdom of grace, the catechism admonishes us to pray “that he would be pleased so to exercise the kingdom of his power in all the world, as may best conduce to these ends.” As J.G. Vos explains,

We pray for the extension and continuance of the kingdom of grace, the hastening of the kingdom of glory, and the success of the kingdom of power for its appointed ends. Note that the kingdom of power is not an end in itself, but a means to the furtherance of the kingdom of grace and the hastening of the kingdom of glory.

Commentary on WLC 191, pg. 557.

Part of Christ’s execution of the office of king is His “restraining and overcoming all [the Church’s] enemies, and powerfully ordering all things for his own glory and their good: and also in taking vengeance on the rest, who know not God, and obey not the gospel” (WLC 45). Christ does not act as Mediator over His enemies (unless He choses to save them and bring them into His kingdom of grace), but He does exercise His kingly power over His enemies (Ps. 110:5-7). The nations are Christ’s “inheritance” and obligated to “serve the Lord with fear” and to “kiss the Son” lest He “dash them in pieces like a potter’s vessel” (Ps. 2). “For the nation and kingdom that will not serve thee shall perish; yea, those nations shall be utterly wasted” (Is. 60:12). Natural disasters (Ps. 46:8), war (Is. 10:5-6), famine and pestilence (Jer. 14:11-2), giving a people over to their sin (Rom. 1:18-32), etc. Christ has control over all these things and uses them according to the council of His will and in His perfect timing to cause peoples to repent (2 Chron. 7:13-14) thus bringing them in to the kingdom of grace, or to remove the wicked off the face of the earth (Luke 17:26-37). 

In the exercise of His regal office, He governs all providential events and revolutions so as to promote the ultimate glory and triumph of His kingdom.

Archibald Alexander, A Compend of Bible Truth, pg. 94.

Matthew Henry, in his commentary on Eph. 1:22 similarly points out that Christ being raised from the dead and seated at the right hand of the Father “far above all principality, and power, and might, and dominion, and every name that is named, not only in this world, but also in that which is to come: and hath put all things under his feet, and gave him to be the head over all things to the church” means that He uses His kingdom of power for the good and special advantage of the Church:

…he is entrusted with all power, that is, that he may dispose of all the affairs of the providential kingdom in subserviency to the designs of his grace concerning the church.

George Gillespie likewise recognizes the kingdom of power in relation to the kingdom of grace in this passage:

Eph. 1:21-23…doth plainly hold forth a twofold supremacy of Jesus Christ: one over all things, another in reference to the church only which is his body, his fulness, and to whom alone he is Head, according to that text.

Aaron’s Rod Blossoming, pg. 93.

Magistracy in the Kingdom of Power

Additionally, WLC 191 says that the civil magistrate ought to countenance and maintain the visible church, and the confession likewise teaches that the magistrate has the authority and duty to ensure “that unity and peace be preserved in the Church, that the truth of God be kept pure and entire; that all blasphemies and heresies be suppressed; all corruptions and abuses in worship and discipline prevented or reformed; and all the ordinances of God duly settled, administered, and observed” as well as the power to call synods (WCF 23:3).

The magistrate has duties to the moral law of God as he is a man who is under it, regardless of whether he is a Christian and a member of the covenant of grace. The application of penalties is not about redemption, but justice. Further, two kingdom theology reinforces the necessity of establishment of religion. Not only does the magistrate have duties to God as Creator, but under the New Testament he is duty bound to submit to Christ’s mediatorial rule by establishing the Church (Ps. 33:12), and covenanting with God to further the kingdom of grace as a nursing father (Is. 49:23; 60:16). This means bringing the nation into the church, which is the kingdom of grace, by recognizing the visible catholic church within his borders. This is why a generic, trinitarian establishment is insufficient. The magistrate must recognize the visible Church as an institution, not merely protect an invisible reality.

It is God’s purpose to set up one kingdom and demolish the other, not only in the hearts of particular men, but in kingdoms and nations and public societies. Jesus Christ was appointed to be not only ‘king of saints‘ (Rev. 15:3), but ‘king of nations‘ (Jer. 10:7); and therefore not only to erect Himself a throne and a government in the hearts of His people, but to have His religion owned and countenanced, and supported by nations and kingdoms and public societies of men.

Thomas Manton, Sermon on Joshua 6:26, Works, Vol. 18, pg. 34.