When should someone be excommunicated or should they be at all?
The Purpose of Discipline
In our thinking, our friends would never wound us and our enemies would never help us, but the Proverbs say “Faithful are the wounds of a friend; profuse are the kisses of an enemy” (Prov 27:6), and “Blows that wound cleanse away evil; strokes make clean the innermost parts” (Prov 20:30) so we have to shift our human thinking toward how God looks at discipline. A parent that fails to keep their children safe by not disciplining them shows that they really don’t care, because if you discipline them in order to help them grow and survive childhood, you show you love them enough to protect them by disciplining them, so how could our friends wound us for our own good? The Bible tells us that God loves us enough to discipline us when we need it. The author of Hebrews writes, “My son, do not regard lightly the discipline of the Lord, nor be weary when reproved by him” (Heb 13:5), because “the Lord disciplines the one he loves, and chastises every son whom he receives” (Heb 13:6), so if you are being disciplined by God, as we all are on occasion, then it is an expression of His love and it shows He deeply cares for you and me.
When Not To Discipline
We don’t want to make a mistake and try to excommunicate someone who is doing something that is considered a grey area or a non-essential. It would be like trying to excommunicate someone because they don’t believe in the rapture or they believe in speaking in tongues while we do not. This is not something that is vital to a church’s fellowship, but if they were gossiping and making false accusations against church members, then that is something that should be examined. We had a church leader who was accused by someone else but the accusation was based upon a false witness or gossip. The Bible says through the Apostle Paul, “Do not admit a charge against an elder except on the evidence of two or three witnesses” (1st Tim 5:19), so one person’s witness is not enough and there is no reason to base an accusation upon one person’s testimony. It takes at least two or three in this case, so to discipline or excommunicate a church member for things that are not hurting the body of Christ, the church, and that does not concern heresy or false teaching, is to not be biblical and is contrary to what Jesus taught about this (Matt 18:15-20). The Old Testament taught the very same thing as Moses wrote, “A single witness shall not suffice against a person for any crime or for any wrong in connection with any offense that he has committed. Only on the evidence of two witnesses or of three witnesses shall a charge be established” (Deut 19:15).
When To Discipline
The very first time we hear the word “church” in the New Testament is when Jesus is speaking about disciplining a brother or sister. He says “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” (Matt 18:15). Hopefully, that takes care of the issue, “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” (Matt 18:16), and “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” (Matt 18:17). Of course, church discipline should be used cautiously and only in cases where the body itself is being hurt. The earlier example of gossip is a good reason to speak to the person but if that doesn’t work, it may take 2 or 3 others to come along and speak with that person. If that fails to stop the member from sinning, then excommunication is the only other option. Certainly, all attempts at disciplining or counseling  should be done first before such drastic action is taken, but if the church is being divided or hurt due to another member’s sin, then that person must be purged from the church…at least until there is a change of heart or repentance and remorse for their actions.
Room for Repentance
After a person has been disciplined, this doesn’t mean the church door is to remain shut to him or her forever. That leaves no room for repentance. The Apostle Paul, to the church at Corinth, about a sinning brother wrote “you should rather turn to forgive and comfort him, or he may be overwhelmed by excessive sorrow” (2nd Cor 2:7), and “I beg you to reaffirm your love for him” (2nd Cor 2:8). When a brother or sister is disciplined by the church, the church must leave room for repentance, so Paul wrote, “Brothers, if anyone is caught in any transgression, you who are spiritual should restore him in a spirit of gentleness. Keep watch on yourself, lest you too be tempted” (Gal 6:1), so we cannot keep someone out of the church for one offense if they have repented, otherwise the church would be an empty building because we too sin, but when a sinning member refuses to repent and ongoing sin hurts the body of Christ and the witness of the church, then the whole lump (the church) can be affected since “A little leaven leavens the whole lump” (Gal 5:9).
Our church had to go through this a few years ago and it is a very painful process…and not just for the member being excommunicated. We had gossip coming back to the church about a certain member who was supposed to be teaching something that he was not teaching, and so when the rumor came back that one of our teachers was teaching heresy, we knew it was a church discipline issue. The teacher was not teaching heresy and we knew this because we were all in this same class that he was teaching and there wasn’t a hint of it. Later, that same person assassinated the character of another church member by lying to others in the community about him. After we spoke with her once and it happened again, we had 3 other church members meet with them (including me) and tell them that if the gossip didn’t stop, they would have to face church discipline. It didn’t stop and today that person is not part of our church….at least yet, because we are praying she is restored to the body of Christ and that she repents of this gossip, but until then, we have to keep the church as pure as possible. I don’t mean sinless because the building would be empty, but serious, church-dividing issues cannot be allowed in the church because, ultimately, we are responsible for the church to Christ and He will hold us all accountable.
Related reading: Church Discipline 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), Crossway Bibles. (2007). ESV: Study Bible : English standard version. Wheaton, Ill: Crossway Bibles. Used by permission. All rights reserved.