Divine spells are granted by Gods or other beings. The caster must rely on them for their power and stay in good favor with their patron lest they be denied it.
Shamans commune directly with spirits for their powers. Witches commune indirectly with their spirit patron through their familiar.
Clerics and Paladins pray to Deities and are granted their spells.
Inquisitors pray to the All-Being or the Tormentor to receive their abilities.