1 Corinthians 6:16

16. Know ye not that he that is joined to an harlot He brings out more fully the greatness of the injury that is done to Christ by the man that has intercourse with an harlot; for he becomes one body, and hence he tears away a member from Christ’s body. It is not certain in what sense he accommodates to his design the quotation which he subjoins from Genesis 2:24. For if he quotes it to prove that two persons who commit fornication together become one flesh, he turns it aside from its true meaning to what is quite foreign to it. For Moses speaks there not of a base and prohibited cohabitation of a man and a woman, but of the marriage connection which God blesses. For he shows that that bond is so close and indissoluble, that it surpasses the relationship which subsists between a father and a son, which, assuredly, can have no reference to fornication. This consideration has led me sometimes to think, that this quotation is not brought forward to confirm the immediately preceding statement, but one that is more remote, in this way — “Moses says, that by the marriage connection husband and wife become one flesh, but he that is jointed to the Lord becomes not merely one flesh, but one spirit with him.” And in this way the whole of this passage would tend to magnify the efficacy and dignity of the spiritual marriage which subsists between us and Christ.

If, however, any one does not altogether approve of this exposition, as being rather forced, I shall bring forward another. For as fornication is the corruption of a divine institution, it has some resemblance to it; and what is affirmed respecting the former, may to some extent be applied to the latter; not that it may be honored with the praises due to the former, but for the purpose of expressing the more fully the heinousness of the sin. The expression, therefore, that they two become one flesh, is applicable in the true and proper sense to married persons only; but it is applied to fornicators, who are joined in a polluted and impure fellowship, meaning that contagion passes from the one to the other. For there is no absurdity in saying that fornication bears some resemblance to the sacred connection of marriage, as being a corruption of it, as I have said; but the former has a curse upon it, and the other a blessing. Such is the correspondence between things that are contrasted in an antithesis. At the same time, I would prefer to understand it, in the first instance, of marriage, and then, in an improper sense, of fornication, in this way — “God pronounces husband and wife to be one flesh, in order that neither of them may have connection with another flesh; so that the adulterer and adulteress do, also, become one flesh, and involve themselves in an accursed connection. And certainly this is more simple, and agrees better with the context.