This passage is what I think of as Jesus' wisdom for conflict management. When we're having trouble with someone the easiest thing is to tell our friends about it, but that generally makes things worse. The scarier, but better way to start is by going to the person we're struggling with. There are plenty of situations in which this isn't an option, especially situations of abuse, but many of our most common conflicts can be solved one on one.
15“If another member of the church sins against you, go and point out the fault when the two of you are alone. If the member listens to you, you have regained that one. 16But if you are not listened to, take one or two others along with you, so that every word may be confirmed by the evidence of two or three witnesses. 17If the member refuses to listen to them, tell it to the church; and if the offender refuses to listen even to the church, let such a one be to you as a Gentile and a tax collector.
18Truly I tell you, whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven. 19Again, truly I tell you, if two of you agree on earth about anything you ask, it will be done for you by my Father in heaven. 20For where two or three are gathered in my name, I am there among them.”