I do not think 2 Cor. 6:14 is a universal prohibition forbidding every sort of social relationship with unbelievers. For then, as Paul said elsewhere, we would have to go out of the world and believers already married to unbelievers would have to divorce them, which Paul does not advocate. I think he means at least things like marrying known unbelievers (1 Cor. 7) and participating in pagan rituals (1 Cor. 10:14-22). He dealt with these things in the first letter to Corinth.
BTW, when you take a job that entails submitting to an unbelieving employer, you are, in effect, selling your skills (not your entire being) to him for a price. IOW, you are going into business with him. You promise work; he promises money. Paul dealt with that, too, but never advocated not working for unbelievers.
I am of the opinion that the Bible does not forbid business partnerships
with unbelievers, though these must be entered into with great care.
Dr. Richard Barcellos is associate professor of New Testament Studies. He received a B.S. from California State University, Fresno, an M.Div. from The Master’s Seminary, and a Th.M. and Ph.D. from Whitefield Theological Seminary. Dr. Barcellos is pastor of Grace Reformed Baptist Church, Palmdale, CA. He is author of Trinity & Creation, The Covenant of Works, and Getting the Garden Right. He has contributed articles to various journals and is a member of ETS.
Courses taught for CBTS: New Testament Introduction, Biblical Hermeneutics, Biblical Theology I, Biblical Theology II.