1 Corinthians 7:17 But as God hath distributed to every man, as the Lord hath called every one, so let him walk. And so ordain I in all churches.
Paul is encouraging the Corinthians here to serve in the capacity that you called into no matter what state you are in. If you are married do not divorce your spouse to serve the Lord but stay together and do it as one. If your are single and God gives you a calling serve Him in that calling as a single person devoting all you have to it. Just serve where you were called, and how you were called. The Corinthians were not happy with there way of life in many areas, marriage, slavery, and some just to use there freedom in Christ to sin. This passage plainly repeats the basic principal that Christians should be willing to accept the marital condition and social situations into which God has placed them and always be content to serve Him there until He leads them elsewhere.