Holding in anger is the virtue of slaves. The Christian bias against anger exists because early Christians were slaves rather than masters. If early Christians had not been forced to hold their tongues (being gentle as doves and sneaky as snakes), Western men would have a healthier relationship with anger.
Aristotle approved of anger, when at "the right time, and for the right purpose and in the right way." As Dr. Bruce Banner was fond of saying, "don't make me angry. You wouldn't like me when I'm angry." People wouldn't listen, and yet they'd still blame the Hulk.
It is usually scoundrels and passive-aggressive who preach against anger. It is of course in their best interests to disarm the very people they seek to harm.
I enjoy being angry. It fuels my soul and moves my body. You wouldn't like me when I'm angry. Please make me angry.