Immoral believers are to be disciplined. Church discipline includes separation from other believers. First Corinthians 5 is devoted to this matter. Therefore put away from among yourselves that wicked person. Sometimes a believer must break fellowship with another believer.
Disorderly believers are to be avoided.
The disorderliness is in the area of practical application of truth which had been taught. Inconsistent, unscriptural behavior is subject to reproof and if not corrected, the believer is to withdraw or separate himself from those who refuse to be corrected. Disobedient believers are to be avoided. And if any man obey not our word by this epistle, note that man, and have no company with him, that he may be ashamed. Disobedience here includes both doctrinal and practical matters.