From the publisher's blurb:
More than in many roleplaying games, Busiris is dominated by its Deities. The people of the Empire worship six main Deities and a host of minor spirits and their ancestors. This worship is direct and heartfelt, there are no atheists in the Empire as the evidence of these deities’ existence is seen every day.
Nothing happens in the Empire without the acquiescence of the Temples, and even the Emperor - a living Deity himself, has to take into account their needs and wishes. A wise Emperor will set each Temple off against its rivals, a foolish one will be dominated by one or more of them.