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.
The Meaning of Christ’s Ascension
Frank Houghton - Eager to Glorify God
Hilary of Poitiers and the Wonder of the Triune God
“He Who upholds the universe, within Whom and through Whom are all things, was brought forth by common childbirth; He at Whose voice Archangels and Angels tremble, and heaven and earth and all the elements of this world are melted, was heard in childish wailing. The Invisible and Incomprehensible, whom sight and feeling and touch cannot gauge, was wrapped in a cradle.”
Basic information – four ideas
(Rev. 1:17, 18)
Walking with God