Certainly none of us can go through a day without interacting with non-Christians.
However, when we have decisions to make about contractual work or other types of business where our quality of life will be affected, we will be better off entering into relationships with people and companies with good reputations and high integrity.
Let God guide you. In everything we do in life, if we will simply seek Him for direction and allow Him to unfold His plan for us, we can be happily surprised when we see the outcome.
So, ask Him what to do with your business decisions. And do your due diligence in checking people and companies out and in fulfilling your part of making good decisions.
Resource: Go back to your December 2010 Believers’ Voice of Victory magazine, and read John Copeland’s article, "The Business of Forgiveness," for some good insight in doing business.