But if the unbeliever leaves, let him go. The believing brother or sister is not bound in such cases. God has called you to live in peace.
15. But if an unbeliever depart. This is the second department of his statement, in which he sets at liberty a believing husband, who is prepared to dwell with an unbelieving wife, but is rejected by her, and in like manner a woman who is, without any fault on her part, repudiated by her husband; for in that case the unbelieving party makes a divorce...
In this paragraph the apostle gives them direction in a case which must be very frequent in that age of the world, especially among the Jewish converts; I mean whether they were to live with heathen relatives in a married state. Moses's law permitted divorce; and there was a famous instance in the Jewish state, when the people were obliged to put away their idolatrous wives, Ezr 10:3.
Commenting on 1 Corinthians 7:10-16
But if the unbelieving depart,.... If the unbelieving party, man or woman, separate themselves from the believing party on account of religion, and in hatred to it, and will not live with the believer unless Christ is denied, his Gospel abjured, and his ordinances and worship relinquished: let him depart; he or she, though not without making use of all proper means to retain them...