2 Thessalonians 3:14

And if any man obeyeth not our words by this epistle, note that man, that ye have no company with him, to the end that he may be ashamed.

This is a further word on what was meant above by "withdraw yourselves." It is all social intercourse, visitation, companioning with offenders that must be ceased. Christians are simply not to mix with persons living in open rebellion against the teachings of the Lord. The purpose of such an ostracism is that it might produce shame and repentance on the part of the offender and result in his restoration.