The experience that players sacrifice is not experience for the god, it is glory points that the god can spend on assorted supernatural infrastructure.
Most gods will grant powers to their followers in return for their worship. The followers gain the advantages of these powers by equipping the god's holy symbol (usually a necklace).
The god has to maintain a piece of supernatural infrastructure to keep the powers functioning. As the power is used, the god's supernatural resources are consumed.
Players may sacrifice up to 100 mils (10%) of their earned experience to their gods. Gods may specify a minimum sacrifice. If a player tries to worship a god and does not offer enough mils, the command will fail.
Players may worship more than one god, giving each a fraction of their experience, with the total not exceeding 100 mils.