"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. For the unbelieving husband is sanctified by the wife, and the unbelieving wife is sanctified by the husband: else were your children unclean; but now are they holy.
But if the unbelieving depart, let him depart. A brother or a sister is not under bondage in such cases: but God hath called us to peace. For what knowest thou, O wife, whether thou shalt save thy husband? or how knowest thou, O man, whether thou shalt save thy wife? But as God hath distributed to every man, as the Lord hath called every one, so let him walk. And so ordain I in all churches." (I Corinthians 7:12-17)
Paul has now come to an area where God has not given specific direction, and he will give his opinion, based on the word of God, and the Holy Spirit's leadership. The same standard of marriage and staying with your mate applies if the unsaved one desires to keep the marriage despite the others Christianity. This is not different.
Certain religious and ethnic groups teach theirmembers that if a member of their family leaves their group for a different one, they are to cut off all ties and refuse to associate with them. When a member of these groups become a Christian, their mate, and their family may well leave them for their Christianity. God is not willing for us to sacrifice our relation to him to maintain peace in such a situation. If they threaten to leave because you serve God, allow them to go. Don't stop serving God to keep them. They have made the choice.
On the other hand, the Christian is not to break the bond God has created just because the other is not a Christian. Christians need to avoid involvement with non christians, according to II Corinthians 6:14. "Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?" Nevertheless, this does not set aside the action of God in bonding them in marriage. God will sanctify the offspring, so that they are not a product of sin. Once God has joined them, separating them is sin. The Christian should not be the one committing the sin.
There is the possibility of the Christian winning the unsaved to Christ, which needs to be taken into account. I Peter 3:1-2 stresses the wife's opportunity. "Likewise, ye wives, be in subjection to your own husbands; that, if any obey not the word, they also may without the word be won by the conversation of the wives; While they behold your chaste conversation coupled with fear." By yielding to her husband, and living a Godly, pure life, and being respectful, she may win her husband. To do so will require learning to walk in the Spirit, not in the flesh, not focused on the things of the world, and giving no inkling of infidelity.The husband has the same opportunity, as I Peter 3:7 informs us. "Likewise, ye husbands, dwell with them according to knowledge, giving honour unto the wife, as unto the weaker vessel, and as being heirs together of the grace of life; that your prayers be not hindered." He needs to recognize that physically she is not as strong as he is, and that as a Christian she3 is his equal, not his slave. They should function like a team of surgeons, each having his own area of expertise, and each able to function independently, but working together to accomplish something greater than either could accomplish alone. By treating his wife in such a fashion, He may win her to Christ. Failure to treat her this way, whether Christian or not, is sin.
Whatever ones situation may be, we need to recognize that God has brought us to that point, and rejoice that he is in charge. Whether we got to this point as a result of our own actions, or the actions of others, God has caused it to turn out this way. Rather than rebelling, trust him and allow him to have his way. Don't try to force change. Our salvation is not dependent on our physical state, and neither is our spiritual walk.
"Is any man called being circumcised? let him not become uncircumcised. Is any called in uncircumcision? let him not be circumcised. Circumcision is nothing, and uncircumcision is nothing, but the keeping of the commandments of God. Let every man abide in the same calling wherein he was called.
Art thou called being a servant? care not for it: but if thou mayest be made free, use it rather. For he that is called in the Lord, being a servant, is the Lord's freeman: likewise also he that is called, being free, is Christ's servant. Ye are bought with a price; be not ye the servants of men. Brethren, let every man, wherein he is called, therein abide with God." (I Corinthians 7:18-24)
If we have the opportunity to make a change that would free us to serve God more freely, we should take it, but we should not make changes that reduce our freedom to serve God. Having your own business, for example, may reduce rather than increasing your freedom.