In Second Corinthians, the Bible contains a widely cited teaching against interfaith relationships:
“Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness? And what concord hath Christ with Belial? or what part hath he that believeth with an infidel? …Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you.” (6:14-17)
Entire sites are devoted to this passage; the cited one says sternly, “If you are involved in a relationship with an unbeliever, and are not married, I would urge you to think very seriously about ending this relationship. God’s Word must be obeyed.”
It’s not just Christianity where this problem arises. I recently got an e-mail from a Muslim woman asking my advice about marrying her ex-Muslim, now atheist, boyfriend:
i wouldn’t mind sacrificing anything for him…
here’s my problem: in islam, we CANNOT marry a non believer. Its forbidden. If i do marry him it’s gonna be a life long sin. thats the deal.
…im not sure what to do… unless he converts (or i do) none of us could be together.
We may cite holy wars and inquisitions, but this is a far more common, and more often overlooked, way in which religion causes harm: it divides people who could otherwise be happy together. This is most visible in the case of gay marriage, where tyrannical religious bigots are intruding into the lives and relationships of others. But it does almost as much harm within relationships, where religious people are forced to break off relationships with the ones they love because of beliefs which teach them that their love is a sin.
This problem almost always arises in the fundamentalist faiths which teach that theirs is the only true way and that all other beliefs bring only misery and unhappiness in life. A believer who marries an atheist, or a theist of another sect, would discover the falsehood of this teaching and undermine the basis of their belief, so it’s little wonder that these sects would want to keep their members isolated and relating only to each other.
If two people have real and serious differences of opinion on subjects that could harm their relationship, then it’s probably best that they stay apart. But if they’re committed to being together and willing to compromise to overcome those differences, then that should be their choice to make. (Since every couple has their differences, it’s the intent to bridge those gaps that’s by far the most important thing.) A blanket ban on interfaith dating, however, is a cruel and unjustifiable law born out of fear. People should be happy together, and nothing takes precedence over that – particularly not bowing to the whims of imaginary dictators. If anything can be called “sin”, then lying, cheating or harming others are the only acts that can or should qualify. The genuine love that people feel for each other is not a sin and never can be, and any religion which says otherwise is a false and wicked creed that does not deserve our allegiance.