As Hamsterbait pointed out, "
(1 Timothy 5:20) "Reprove before all onlookers [those in the Christian congregation] persons who practice sin, that the rest [thosein the Christian congregation] also may have fear."
Also -
(Matthew 18:17) If he does not listen to them, speak to the congregation. [not a couple of Elders] If he does not listen even to the congregation, let him be to you just as a man of the nations and as a tax collector. [then disfellowship him!]