The Lord very frequently addresses us in the character of a husband… As He performs all the offices of a true and faithful husband, so He stipulates for love and conjugal chastity from us; that is, that we do not prostitute our souls to Satan… Therefore, as the purer and chaster the husband is, the more grievously is he offended when he sees his wife inclining to a rival; so the Lord, who has betrothed us to Himself in truth, declares that He burns with the hottest jealousy whenever, neglecting the purity of His holy marriage, we defile ourselves with abominable lusts, and especially when the worship of His Deity, which ought to have been most carefully kept unimpaired, is transferred to another, or adulterated with some superstition; since, in this way, we not only violate our plighted troth, but defile the nuptial couch, by giving access to adulterers.
Institutes II, vii, 18.
