“ … If any one idea dominates the teachings of Jesus, it is his opposition to the self-righteousness of the righteous. … In fact, Jesus seems to have been in perpetual conflict with the good people of his day … "
I would disagree that this aspect is the singular part of Jesus' teachings. But, it's certainly a major theme.
Hat-tip: Andrew Sullivan, who provides a longer passage
The painting above is "Woe unto You, Scribes and Pharisees" or " Malheur à vous, scribes et pharisiens" by James Tissot. It is the property of the Brooklyn Museum of Art.