Paladins are lawful good. They are the champions of law and goodness in balance. The force that empowers a paladin seems to be a universal constant and can be independent of direct deity intervention.
This does not make them lawful stupid or lawful arrogant (usually).
Paladins may exist within various clerical orders, specifically those of a LG and martial ethos, but since a portion of their power comes from a universal source, some of the more chaotic or neutral religions favor other forms of holy champion in their orders.
The ankh is a favored symbol of paladins, in that it represents both life and light, and order.
There exist rumors of fallen paladins, who were seemingly corrupted by the influence of evil deities or some unknown force of darkness, who fight to destroy all goodness and light. (LE)