What should a Christian do if their unbelieving spouse wants to stay married?
If an unbelieving spouse is pleased to dwell with the believing spouse, the believer should not put them away or leave. Scripture says to let them not depart; the believer is to stay with the unbelieving spouse and remain married.
The teaching explains that the Lord's command to the married is that the wife should not depart from her husband, and if she departs she should remain unmarried or be reconciled; likewise the husband should not put away his wife. Then, to the rest, the instruction is that if an unbelieving spouse is pleased to dwell with the believing spouse, the believer is not to put them away or leave. The conclusion given is 'Stay with him.' This reflects God's view of marriage rather than society's or a denomination's view, and every sin remains forgivable.
But to the rest speak I, not the Lord: If any brother hath a wife that believeth not, and she be pleased to dwell with him, let him not put her away.
And the woman which hath an husband that believeth not, and if he be pleased to dwell with her, let her not leave him.