Matthew 18 / I Corinthians 5-6
Matthew 18:15-17 Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother. 16But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established. 17And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto thee as an heathen man and a publican.
Ok now what? Paul shows us in:
I Corinthians 5:3-5 For I verily, as absent in body, but present in spirit, have judged already, as though I were present, concerning him that hath so done this deed,  4In the name of our Lord Jesus Christ, when ye are gathered together, and my spirit, with the power of our Lord Jesus Christ, 5To deliver such an one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus.
Several key points: One you can not lose your salvation but you can lose your life. Second the church has a responsibility to purge sin in it self. Third there are sins unto death I John 5:16-18 and sins not unto death. Forth only saved people can commit them. Fifth we are the Israel of God in the Spirit see I Corinthians 10:18 There is an Israel after the flesh and one after the Spirit. Paul continues and tells you why this must be done.
I Corinthians 5:6 Your glorying is not good. Know ye not that a little leaven leaveneth the whole lump?
I Corinthians 5:11-13 But now I have written unto you not to keep company, if any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner; with such an one no not to eat. 12For what have I to do to judge them also that are without? do not ye judge them that are within?  13But them that are without God judgeth. Therefore put away from among yourselves that wicked person.
These are not unsaved! They are saved and not walking right before Yahuweh. They have not judged themselves and utilized the blood of communion and are offending the Holy Spirit of Jesus by which they are sealed, protected and preserved. Ephesians 4:30
I Corinthians 6:9-11 Know ye not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind, 10Nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners, shall inherit the kingdom of God. 11And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God.
Paul is explaining these sins to the world are unto destruction of body and soul to the world, to us that are saved it will destroy our body also.
Father open eyes by the power of Your word upon our hearts, let us see and truly know the great gift of salvation and our duty to Your son for His blood that has cleansed us of sins past. Using that same blood through confession to judge ourselves and body broken to guide my heart to repentance, I love you Yahushua and do judge myself.
Halle lu YAH