Intolerance — or an unwillingness to accept the beliefs or behavior of someone different from you — is not a quality you want to have. Intolerance is what leads to hate crimes and discrimination.
The word intolerance comes from a combination of the Latin in- meaning “not” and tolerantem meaning "to bear, endure.” Intolerance is not being able to bear or endure beliefs that are different from your own. You may commonly hear of it used with respect to religious intolerance, which is an unwillingness to accept different religious beliefs.