Read this passage and open each verse for the full verse feed and commentary tools.
17Now I beseech you, brethren, mark them that are causing the divisions and occasions of stumbling, contrary to the doctrine which ye learned: and turn away from them. 18For they that are such serve not our Lord Christ, but their own belly; and by their smooth and fair speech they beguile the hearts of the innocent. 19For your obedience is come abroad unto all men. I rejoice therefore over you: but I would have you wise unto that which is good, and simple unto that which is evil.
Romans 16:17-19 (ASV)