Do not be yoked together with unbelievers. For what do righteousness and wickedness have in common? Or what fellowship can light have with darkness?
— 2 Corinthians 6:14
There is probably no other Scripture that has produced more conflict for ministers than this one. While not applying just to marriage, this verse is a powerful reminder that when we make life-long partnerships with those who do not share our deepest values, we are endangering our spiritual health. Just as God would not allow the Israelites under the Law to yoke a donkey and an ox together because it would ultimately break them both down, Paul reminds Christians that the same is true in their deepest relationships as well.
Those in Christ are something other than those who are not in Christ. They are not the same—spiritually—and should not be locked together into any kind of binding relationship. Paul begins to ask a series of questions to show the absurdity of a believer in Jesus being “unequally yoked” with an unbeliever.
Paul asks: what cooperation can there be between virtue and wickedness? Those in Christ have “become the righteousness of God” (2 Corinthians 5:21). Those outside of Christ continue in their status as unrepentant, lawless sinners. The two cannot—must not—be joined together. To do so makes as little sense as trying to join light and darkness in fellowship. It can’t be done. As soon as the light arrives, the darkness must vanish.
It’s essential to realize Paul is not saying believers should never associate with unbelievers, at all (1 Corinthians 5:9–10). Believers should continue to live and function in the world, which includes contact with unbelievers (1 Corinthians 10:25–26). Rather, Scripture’s teaching here is that Christians must not enter into binding, partnering agreements with non-Christians.