until our minds become intent upon the Spirit, Christ, so to speak, lies idle because we coldly contemplate him as outside ourselves—indeed, far from us. We know, moreover, that he benefits only those whose “Head” he is [Eph. 4:15], for whom he is “the first-born among brethren” [Rom. 8:29], and who, finally, “have put on him” [Gal. 3:27]. This union alone ensures that, as far as we are concerned, he has not unprofitably come with the name of Savior. The same purpose is served by that sacred wedlock through which we are made flesh of his flesh and bone of his bone [Eph. 5:30], and thus one with him. But he unites himself to us by the Spirit alone. By the grace and power of the same Spirit we are made his members, to keep us under himself and in turn to possess him.
John Calvin, Institutes of the Christian Religion & 2, ed. John T. McNeill, trans. Ford Lewis Battles, vol. 1, The Library of Christian Classics (Louisville, KY: Westminster John Knox Press, 2011), 541.