This is amusing...trying so hard to evade and confuse the obvious truth because it doesn't agree with what your men have taught you.
Here's how it works (You can follow along in the pages of your very own Bible if you want):
A brother sins against you. You show him his fault and he listens to you. He repents and asks for and receives the forgiveness of the offended person. God is there with them and approves, placing his stamp of approval on the forgiveness worked out between them, for
"if two of you on earth agree about anything you ask for, it will be done for you by my Father in heaven" (Matthew 18:19). Done! No need for a pope, or a cardinal, or a bishop. No ceremonies or rituals needed. The person is forgiven here on earth and in heaven above. The matter is resolved. End of story.
But if he
doesn't listen to you the offended brother brings in two or three witnesses. Jesus cites the scriptures that stipulate that a person is not to be condemned and treated as a pagan or a tax collector without the testimony of two or three witnesses. The offended person
by himself could not pass this judgment. That would be unlawful. And so this is not to establish whether or not what he did is a sin (though he may well be insisting it is not, lol),
but rather to convict this person of their wrong doing. This is the verse Jesus cites in Matthew 18:16...
"One witness is not enough to convict a man accused of any crime or offense he may have committed. A matter must be established by the testimony of two or three witnesses." Deuteronomy 19:15
So we can see this is not about whether or not what the man did is a sin. It's about whether or not he really committed it, and to be convicted if he did. The hope is, of course, that the sinner will acknowledge his guilt and ask for and receive forgiveness, for "if two of you on earth agree about anything you ask for, it will be done for you by my Father in heaven. For where two or three come together in my name, there am I with them." (Matthew 18:19-20). Once again, no popes, no cardinals, no bishops, no ceremonies, no rituals required. The matter of forgiveness and reconciliation can be settled in the earth and in heaven by those present.
Now, if the brother still doesn't acknowledge his guilt and ask for and receive forgiveness, that is when the matter is taken before the whole congregation. It doesn't matter if Sally, or Ralph, or Gerald aren't in attendance at that meeting. It's not a vote. The matter of forgiveness and reconciliation could not be settled by the parties and witnesses involved so the matter is taken before the pastor, elders and congregation. The matter is reviewed, perhaps discussed, all under the authority and guidance of the pastor and elders of the congregation. And if the sinner still does not repent and receive forgiveness he is turned over to his sin and is to be regarded by the whole congregation as a pagan or a tax collector (IOW, an unbeliever).