1 Corinthians 7:15

‘Yet if the unbelieving one separate themselves, let them depart. The brother or the sister is not under bondage in such cases.'

Where the unbelieving partner seeks a divorce, or walks out because the person has become a Christian, or turns the Christian out, then no blame can attach to the Christian. They may let them depart. They need not feel bound to try to sustain, and make great efforts to preserve, what has become an impossible marriage, especially as this would usually mean that the other partner was seeking to pressurise them and the children into turning their backs on Christ.

‘Not under bondage in such cases.' This may simply mean that they need not feel bound to make excessive efforts to prevent it, or it may mean that they are seen as released from their marriage and may therefore divorce the unbeliever and marry a Christian. This latter would seem intrinsic in the words, (although not directly referred to), in view of the invidious position a Christian woman may find herself in in such a case, especially if she had children to look after and bring up. It would also seem to be confirmed by seeing this position as contrasted with that in 1 Corinthians 7:11 where the woman was bound to remain single. But if so it is the exception that proves the rule and arises because of the decision of the non-Christian partner. However, Paul's emphasis is on the fact that she need not feel under a burden to continue the marriage. It cannot be seen as a general approval of remarriage. Earlier Paul has made clear that in general the opposite is the case.

We can compare this case with that of the Ezra 9-10 (although that is more like the case of a believer actually marrying an unbeliever). There the presumption must be that having put away their idolatrous wives they were permitted to marry again although it does not actually say so. Permission was presumably given by default.