Evil is an axis of alignment most commonly associated with acts that harm others. Evil people and creatures have little to no compassion for others, and will kill whenever it suits their purpose. These evil acts can be done out of selfishness and greed, for sport, or at the behest of an evil master.1 Evil influences in religious spheres may be termed profane as opposed to sacred.
Paizo published Faiths of Corruption, Princes of Darkness, Lords of Chaos, and Horsemen of the Apocalypse regarding evil-aligned deities and outsiders, and Champions of Corruption and Agents of Evil regarding evil-aligned people and organizations.
For additional as-yet unincorporated sources about this subject, see the Meta page.