The opposite of un-righteous is righteous. Righteous is defined as being morally right or justifiable. Its synonyms include good, honest, virtuous, and honorable. On the other hand, un-righteous means not morally justified, evil, or wicked. Antonyms to un-righteous include ethical, fair, lawful, decent, and upright. These words describe actions or behaviors that are morally right and just. It is important to know the difference between the two words because choosing to act righteously can lead to a more just and equitable society. In summary, the antonyms for un-righteous are words that represent just and moral actions.