When we are speaking about "fellowship" we are speaking communion or common union. The example was when Paul ordered the church at Corinth to expel the man guilty of sexual sins.
1 Corinthians 5:1-5 ESV (1) It is actually reported that there is sexual immorality among you, and of a kind that is not tolerated even among pagans, for a man has his father's wife. (2) And you are arrogant! Ought you not rather to mourn? Let him who has done this be removed from among you. (3) For though absent in body, I am present in spirit; and as if present, I have already pronounced judgment on the one who did such a thing. (4) When you are assembled in the name of the Lord Jesus and my spirit is present, with the power of our Lord Jesus, (5) you are to deliver this man to Satan for the destruction of the flesh, so that his spirit may be saved in the day of the Lord.
Kicking him out of the of the church was not unloving. I don't know why we think that any Biblical act of separation is an act representing that we no longer love. We love the man that was expelled and we love the congregation that we saved from his ungodly example. Paul commanded that the church present the man to Satan for the destruction of the flesh. That may sound judgmental and unloving but look at the rest of it. Paul wanted his spirit to be saved in the day of the Lord. There is a lot of different doctrines I could get into on this one but I will stay focused on the topic at hand. Paul revealed his love for the man. The goal of separation and the judgment was for the ultimate goal of reconciliation. We find in 2 Corinthians that the man repented and was restored into the fellowship.
So now having said that the main reason for separation from brothers is so that they be reconciled. And that separation does not mean that we stop loving them. I will get to the first group of people we are to separate ourselves from.
1. SEPARATING FROM CHRISTIAN BROTHERS WHO ARE UNRULY OR DISORDERLY:
This could be separating from an individual or from a corporate body of believers.
2 Thessalonians 3:5-7 ESV (5) May the Lord direct your hearts to the love of God and to the steadfastness of Christ. (6) Now we command you, brothers, in the name of our Lord Jesus Christ, that you keep away from any brother who is walking in idleness and not in accord with the tradition that you received from us. (7) For you yourselves know how you ought to imitate us, because we were not idle when we were with you,
In 2 Thess.3:6 the word "idleness" means morally disorderly. The term "keep away from" in the Greek is to abstain from association. Again this is for protection of the group and the individual from falling into another man's sin. And it is so that the one in sin would have time alone to be convicted of the Holy Spirit and enter reconciliation. Again it is not a love issue. We never stop loving the person in sin.
So what is the process or action of discipline that leads up to our of separating ourselves from a moral disorderly believer?
Matthew 18:15-17 ESV "If your brother sins against you, go and tell him his fault, between you and him alone. If he listens to you, you have gained your brother. (16) But if he does not listen, take one or two others along with you, that every charge may be established by the evidence of two or three witnesses. (17) If he refuses to listen to them, tell it to the church. And if he refuses to listen even to the church, let him be to you as a Gentile and a tax collector.
To be branded as a Gentile and a tax collector means that you are to have no contact especially religious contact, meaning not having them in a religious service with you. I know it goes without saying but for some I feel the need to point out that these are the words of our Lord Jesus Christ.