The players are novices of different religions trying to collect as much good karma as possible. They take turns being the High Priestess, who is the only one who knows the basics of her religion. Maybe treating the High Priestess in a certain way is advantageous or perhaps the way you handle artefacts is important. Each religion has its own rules.
During the ritual, the novices take turns in trying to act appropriately to get karma. The high priestess tries to win over one especially zealous novice, because this will earn her extra karma. The player with the most karma will win.