A bully attempts to control and dominate others, and he or she will use the most underhanded techniques to do so. Many (if not all) bullies suffer from malignant narcissism or another personality disorder. Because they have over-inflated egos, they also feel entitled to special treatment. This means they expect things to always go their way. Anyone who doesn't agree with them is subject to severe punishment. To a bully, other people are objects, to be used in an effort to achieve their objective of absolute power.
You'll find bullies at church, playing up to the pastor and trying to usurp his authority. Church provides the perfect environment for a bully. Christians are called to bear with one another, which is why a lot of bizarre behavior is tolerated, when it would never fly in the corporate world. Being non-judgmental is a lovely virtue. But, at some point, we have to use our discretion, and not stand by when someone else is being abused. This is not virtuous. It's cowardly, and God expects more from us. Our righteousness has to exceed that of the Scribes and Pharisees.
Flickr photo by Rock City Kennels