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? And what agreement hath the temple of God with idols? for ye are the temple of the living God; as God hath said, I will dwell in them, and walk in them; and I will be their God, and they shall be my people. II Corinthians 6:14-16 (KJV)

Many Christians use this passage to emphasize the importance of not marrying an unbeliever. While that application is correct, we need to realize this concept applies to all areas of life. It is important with whom we become affiliated and associated. To get a better feel for these verses, let’s look at a few different versions. I think you’ll find it enlightening.

Don’t link up with unbelievers and try to work with them. What common interest can there be between goodness and evil? How can light and darkness share life together? How can there be harmony between Christ and the devil? What business can a believer have with an unbeliever? What common ground can idols hold with the temple of God? For we, remember, are ourselves living temples of the living God, as God has said: ‘I will dwell in them and walk among them. I will be their God, and they shall be my people’. II Corinthians 6:14-16 (JB Phillips New Testament, PHILLIPS) emphasis mine

Don’t continue to team up with unbelievers in mismatched alliances, for what partnership is there between righteousness and rebellion? Who could mingle light with darkness?  What harmony can there be between Christ and Satan? Or what does a believer have in common with an unbeliever?  What friendship does God’s temple have with demons? For indeed, we are the temple of the living God, just as God has said: I will make my home in them and walk among them. I will be their God, and they will be my people. II Corinthians 6:14-16 (The Passion Translation, TPT) emphasis mine

Don’t become partners with those who reject God. How can you make a partnership out of right and wrong? That’s not partnership; that’s war. Is light best friends with dark? Does Christ go strolling with the Devil? Do trust and mistrust hold hands? Who would think of setting up pagan idols in God’s holy Temple? But that is exactly what we are, each of us a temple in whom God lives. God himself put it this way: “I’ll live in them, move into them; I’ll be their God and they’ll be my people. So leave the corruption and compromise; leave it for good,” says God. “Don’t link up with those who will pollute you. I want you all for myself. I’ll be a Father to you; you’ll be sons and daughters to me.” The Word of the Master, God. II Corinthians 6:14-18 (The Message, MSG) emphasis mine

As Christians, we are called to reach out to the unsaved, which means we do not need to totally isolate ourselves from sinners. However, we need to refrain from attachments with them.

The Message says it well, emphasizing that worldly alliances bring corruption, compromise and pollution to our lives. We are children of the Light, and we have no business making partnerships and covenants with darkness. We must guard our walk with God. We are each the temple of God, and we do not need to introduce the impurity of the world into that temple.

If we want to be close to God, it means distancing ourselves from entanglements with unbelievers.

Do you not know that friendship with the world means hostility toward God? So whoever decides to be the world’s friend makes himself God’s enemy. James 4:4 (New English Translation, NET)