But those who are determined to be rich fall into a temptation and a snare and many foolish and harmful lusts, such as drown men in ruin and destruction.
So basically the servant was as a Christian, to be exemplary in his service, whether he had an unbelieving or a believing master. Now if you had a believing master, he may sort of resent the fact that he still is requiring this of me. After all, we're brothers in Christ and we are believers, you know. But Paul is just exhorting them to have the respect and honor of their masters.