2 Cor. 6:14-18 (ESV)
Do not be unequally yoked with unbelievers. For what partnership has righteousness with lawlessness? Or what fellowship has light with darkness?  What accord has Christ with Belial? Or what portion does a believer share with an unbeliever?  What agreement has the temple of God with idols? For we are the temple of the living God; as God said,
"I will make my dwelling among them and walk among them,
and I will be their God,
and they shall be my people.
 Therefore go out from their midst,
and be separate from them, says the Lord,
and touch no unclean thing;
then I will welcome you,
 and I will be a father to you,
and you shall be sons and daughters to me,
says the Lord Almighty."
Do not be unequally yoked with unbelievers. Though there maybe some wisdom in not marrying an unbeliever, or a person of another faith (hence unbeliever.) I can’t see how this verse has anything to do with that. I know it is applied that way often, but I think it is a stretch. Paul in 1 Corinthians urges those who are married to unbelievers to stay married to them, if at all possible. This bring me to another point about the spiritual headship of husbands and fathers, too many women take this too far. They justify not going to church, or going to a church with which they disagree, by citing the husband as spiritual head. Well, Christ is our Spiritual head, and we listen to him over and above any earthly authority we have. So if husbands are telling wives to do things that they know to be against God’s commands, then don’t do it. A husband actually has no right to tell his wife where to go to church, or not to go to church, or keep her from church in another way. That is actually grounds for divorce, that would be the unbeliever not consenting to remain married. But again this verse isn’t saying all that.
The whole 6th chapter of 2 Corinthians is dealing with the life of the Christian in the Church. Paul begins by asking that they do not receive the grace of God in vain. (So much for “once saved always saved.)” I can’t help but think this verse is Paul returning to the idea of Believers in Christ joining in the temple rites (worship) and sacrifices to pagan Gods. Today we still need to be careful in these things. Christians should not be joining lodges (Masonic or otherwise) with their universalistic teachings, that are embedded in the initiation rites. That is not harmless fun. There are other dangers where this is concerned also. Horroscopes, and other occultic practices playing with Ouija boards, palm readings. Sometimes we think this can be done in fun. But then we yoke ourselves with unbelievers, and not to their benefit or ours. We water down our confession of Christ, who is the only way, the only truth, the only life, we have.