Calvin has already established his understanding of "a twofold government" to which human beings are subject: an inward government in which God rules over the individual human soul for eternal life and an outward government in which God through human government establishes civil justice and outward morality (4.20.1).
Marriage has been instituted by God, but it is not a sacrament. Many are the good things which God has instituted, but that does not make them sacraments, which are, by definition, signs and ceremonies to confirm God's promise to us. The fact that marriage illustrates Christ's relationship to the church does not make it a sacrament either - many are the things that illustrate it, but they are not sacraments.
Recently, a video of Francis Chan surfaced in which he tries to explain what he now believes about the real physical presence of Christ in the Lord’s Supper.
Some find it misguided to praise men. It was, after all, the Corinthian problem that they openly declared their allegiance to men: Apollos, Paul, or Peter. In doing so they caused major divisions in the Corinthian church.
But we are not, I think, to conclude from this that we are never to express our appreciation for the lives of men (and women!) whose gifts have helped not only their own generation but our own also. Surely, this is the meaning of the gallery of the faithful in Hebrews 11.