One of the major differences between ancient Greek religion and many widely practiced contemporary religions is its strong emphasis on contracts. A large part of worship entailed asking specific favors from the gods. Of course, which god you turned to depended on what you wanted. If you wanted justice done, you might turn to Zeus, who was in charge of justice. If you wanted to get into some sneaky business, you'd probably call on Hermes, the god of trickery – just as Orestes does repeatedly in Libation Bearers. In exchange for helping you out with your problems, you would promise something to the gods in return: sacrifices, say, or ritual libations.
Did we say libations? We did. Libations are ritual offerings of liquid, typically water, wine, honey, milk, or oil. There were many occasions when such offerings were made: before dinner, when making a sacrifice, when praying, etc. But one of the most important functions of libations was as offerings to the spirits of the dead. The most prominent spirits of the dead were known as "heroes"; they were thought to inhabit and watch over specific locations – sort of like ghostly watchdogs. The way in which Orestes and Electra make offerings to the spirit of their father Agamemnon is very similar to recorded religious practices involving "heroes," what scholars know today as "hero-cult" or "hero-worship."
Libation Bearers portrays the gods as mainly harmful towards humans.
Libation Bearers does not provide any firm evidence that the gods influence life on earth.