Jesus set the example for shunning sinners, didn't he?
Again...you are being very selective in your theology. Look for example at Jesus' treatment of the money changers in the temple and his indictment of the jewish religous leaders of his time. When he dealt with sinners, he never dismissed their transgressions. In fact he usually confronted them with their sins in order that they might change. He was not some sort or namby pamby liberal, willing to forgive and forget because they had a bad childhood. Jesus understood the grave consequences of rebellion against God and eventually died to pay the penalty for the rebellion of those who would accept his sacrifice that they might find peace with God.
Incidently, your analysis of "judging" overlooks numerous passages in the Pauline epistles which are just as authoritative as the gospels.