“Do not be unequally yoked with unbelievers. For what partnership has righteousness with lawlessness? Or what fellowship has light with darkness?” (2 Corinthians 6:14 ESV)
Paul here is commanding believers not to be yoked together, that is, not to be allied with unbelievers. However, we must realize that when Paul warns the saints not to be unequally yoked with unbelievers, he refers primarily to professing Christians, specifically his opponents at Corinth who taught that he was not a true apostle. He used rather strong and harsh words to label them as ravenous wolves who preached in the name of Jesus a gospel that belied the saving power of His sacrifice on the cross. The unclean and impure are the unbelievers who wrongfully identify themselves as believers and their supporters. These threatened the integrity of church from within. Allowing them to remain unchallenged and even honored in the fellowship of the saints defiled the church, its ministry and worship for it insulted the glory of the Lord. We would be wise to heed this and carefully avoid relationships or fellowship with believers who though they preach from God’s word demonstrate by their lifestyles, deeds and attitudes that they are out only for themselves.
Today, in addition to the above warning, we would define unbelievers as pagans, people of all other religions, and all non-Christians in general. We can then apply this command to the context of mixed marriages and mixed business partnerships. If we love God we will live and work to honor Him above all else, a principle that is hard to follow if we are involved in intimate fellowship with people who do share our faith. First, the principle Paul lays down is that a believer should never under any circumstances, marry a nonbeliever. We are not to enter into an important and intimate relationship such as marriage with an unbeliever for that would dishonor God as well as interfere with our own Christian walk.
A Christian also would be wise not to enter into or run a business in partnership with someone who is not, although admittedly these days this is rather difficult. We are not to work for people or businesses whose stated goals and operating principles are contrary to or hostile toward the kingdom of God. If we do we are working at odds with the Lord and He is not really first in our lives