Charles Ellicott Commentary 1 Corinthians 7:12

"But to the rest say I, not the Lord: If any brother hath an unbelieving wife, and she is content to dwell with him, let him not leave her." — 1 Corinthians 7:12 (ASV)

But to the rest.—Up to this point, the writer has alluded only to Christians; he has spoken of the duties of unmarried persons, of widows, and of those already married. There still remains one class of marriages concerning which differences of opinion existed—namely, mixed marriages. In a church like Corinth, there would have been, no doubt, many cases where one of the partners was a heathen and the other a Christian, arising from the subsequent conversion of only one of the married couple. This subject is addressed in 1 Corinthians 7:12–16. The words are emphatically, “If any man have already a wife,” etc. The case of a Christian marrying a heathen is not alluded to. In 2 Corinthians 6:14, the marriage of a Christian to a heathen is forbidden.

Speak I, not the Lord.—The Apostle has no word of Christ's to quote on this point, as this issue did not arise during our Lord’s life. (See Note on 1 Corinthians 7:10.)

It is to be noticed that the Apostle, in giving his own apostolic instruction on this point, does not use the word “command,” which he applied to our Lord's teaching, but the less authoritative “speak.”

A wife that believeth not.—That is, a heathen. In some modern religious circles, this whole passage has been used (as also 2 Corinthians 6:14) as if by “unbeliever” St. Paul meant a careless Christian, or one who, in modern phraseology, was not “converted.” The Apostle is referring by this designation to heathens. Therefore, the only case to which his teaching could now or ever apply is when two heathens had been married, and subsequently, only one had embraced the Christian faith.

It is to be noticed that both here and in 1 Corinthians 7:13, the phrase “pleased to dwell” refers only to the partner who is a heathen. This is because the Apostle takes for granted that after the instructions he gives here to the Christian partner, no such desire for separation will arise on the Christian's part.