When confronting people, we should use the procedure Jesus offered in Matthew 18:15-17.
“If your brother or sister sins, go and point out their fault, just between the two of you. If they listen to you, you have won them over. But if they will not listen, take one or two others along, so that ‘every matter may be established by the testimony of two or three witnesses.’ If they still refuse to listen, tell it to the church; and if they refuse to listen even to the church, treat them as you would a pagan or a tax collector."
I want to look at this step-by-step for a moment:
Step 1. Talking privately
This isn't usually confrontational at first but merely an attempt to understand where the other person is coming from. Sometimes there are misunderstandings or misconceptions you can come to terms with by just simply sitting down and taking time to talk. If there is an impasse or an offense, forgiveness or repentance may be needed. Be humble and open in your confrontation. Don't go into it judgemental and ready for a battle. Check your motives and heart. Be full of compassion as well. If you cannot get past the one-on-one meeting without resolution and reconciliation, step two may be necessary.
Step 2. Witnesses
Sometimes private conversations are not enough - even when you've tried everything. The witnesses you choose must respected by both parties and willing to defend or oppose both parties. These are not people you are trying to get on your side. Don't pick a "yes man". Don't pick someone who will be for you. You want a mediator. You want someone who can look at both of you and say "you are both wrong". You want someone who you know will always reside with the truth of Scripture. Don't act alone. Get an elder, pastor, small group leader or someone mature in the Faith involved. Remember, the point of this is still reconciliation, not "sick em".
Step 3. Tell It To The Church
This probably is the most misused and misunderstood part. It does not mean run and tell. It is not, at this point, public information to be posted on every Facebook wall and emailed to the entire church. It is not a trial with the congregation as the jury. It is not a public hearing. It is not for the permission to list their name in a sermon. Not everyone in the church should be told as most cannot handle or discern correctly. The point is to tell other mature believers who can help in the reconciliation and restoration process where your attempts have failed. The point is not punishment but restoration. Only in extreme (I mean extreme) situations where this sin affects the entire church should it be brought before the entire church. This is only done by Senior leadership (Senior pastor with elders in agreement). Still, love and restoration are still the motives.
Step 4. Treat Them As A Pagan Or Tax Collector
This also misused and misunderstood. Sure, this is a recognition that they are no longer part of the body - but by their choice alone. It is not booting them out but simply recognizing what has, in fact, already take place by their choices of resisting restoration and repentance. This is not shaming or despising them either. Think about how Jesus treated sinners - especially pagans and tax collectors. He loved them. He didn't pretend they were soul mates. He knew they were not part of the church but still tried to love them back into it. He always confronted sin, but He loved the sinners in the process. Steps 3 and 4 are always the last resort. These steps, especially 4, are only used in situations where continuing, confirmed, unconfessed sin resides.
These last two steps are only done if the leadership of the church supports it and, for the most part, leads it. Go to leadership first before taking action on your own. Don't be a rogue renegade and do these on your own. You'll be as bad as the offender you are addressing. Don't move too quick either on these last two steps. Give time for the Holy Spirit to move. You should pray through situations at length and give lots of room and time for the offender to repent and seek restoration before steps 3 and 4. I would and have even repeated step 1 and 2 a few times before moving on. Remember you don't wrestle against flesh and blood (Ephesians 6:12). People are not your enemy. We also must remember that we are called to the ministry of reconciliation (2 Corinthians 5:18). We must also expose deeds of darkness (Ephesians 5:11). The balance must be walking firmly in truth, loving the sinner, and humbly confronting sin - all at the same time.