We see Calvin’s missions focus in a couple of passages from the Institutes. He urged that in prayer we should “daily desire that God gather churches unto himself from all parts of the earth; that he spread and increase them in number” (Institutes 3.20.42). As we pray, “Your kingdom come,” we are asking “that God may gather churches to himself from all quarters of the world, may extend and increase their numbers, enrich them with his gifts, establish due order among them” (Institutes 3.20.41).
There is a lot more good content in Calvin’s quote:
42. The second petition is, THY KINGDOM COME. . . .
This petition, therefore, is duly presented only by those who begin with themselves; in other words, who pray that they may be purified from all the corruptions which disturb the tranquillity and impair the purity of God’s kingdom. Then as the word of God is like his royal sceptre, we are here enjoined to pray that he would subdue all minds and hearts to voluntary obedience. This is done when by the secret inspiration of his Spirit he displays the efficacy of his word, and raises it to the place of honour which it deserves. We must next descend to the wicked, who perversely and with desperate madness resist his authority. God, therefore, sets up his kingdom, by humbling the whole world, though in different ways, taming the wantonness of some, and breaking the ungovernable pride of others. We should desire this to be done every day, in order that God may gather churches to himself from all quarters of the world, may extend and increase their numbers, enrich them with his gifts, establish due order among them; on the other hand, beat down all the enemies of pure doctrine and religion, dissipate their counsels, defeat their attempts. Hence it appears that there is good ground for the precept which enjoins daily progress, for human affairs are never so prosperous as when the impurities of vice are purged away, and integrity flourishes in full vigor. The completion, however, is deferred to the final advent of Christ, when, as Paul declares, “God will be all in all,” (1 Corinthians 15:28). This prayer, therefore, ought to withdraw us from the corruptions of the world which separate us from God, and prevent his kingdom from flourishing within us; secondly, it ought to inflame us with an ardent desire for the mortification of the flesh; and, lastly, it ought to train us to the endurance of the cross; since this is the way in which God would have his kingdom to be advanced. It ought not to grieve us that the outward man decays provided the inner man is renewed. For such is the nature of the kingdom of God, that while we submit to his righteousness he makes us partakers of his glory. This is the case when continually adding to his light and truth, by which the lies and the darkness of Satan and his kingdom are dissipated, extinguished, and destroyed, he protects his people, guides them aright by the agency of his Spirit, and confirms them in perseverance; while, on the other hand, he frustrates the impious conspiracies of his enemies, dissipates their wiles and frauds, prevents their malice and curbs their petulance, until at length he consume Antichrist “with the spirit of his mouth,” and destroy all impiety “with the brightness of his coming,” (2 Thessalonians 2:8).