Serer religion places one god at the top and then spends almost none of its ritual attention on him. Roog is self-created, the origin of everything, and is described in the tradition as having withdrawn; there is no cult of Roog, no image and no priesthood dedicated to him. He is invoked at the opening and closing of prayers and in the formula that names him as the one who gives and takes. This shape, a single high god who is real but not approached, recurs across West Africa and is one of the reasons the region's religions have been classified so inconsistently.
The pangool are what the religion actually works with. The word is plural; a single one is a fangool. They are the ancestors, and also the spirits attached to particular places, and the two categories are not sharply divided, because an ancestor of standing may become the fangool of the ground the family holds. A household keeps a shrine, sometimes a post, sometimes a stone or a tree, at which libations are poured and requests made. What is asked for is specific: a birth, a recovery, rain, safety on a journey. The pangool are understood to carry these to Roog, and also to act on their own account, and to be offended by neglect in the same way a living relative would be.
The saltigue stands apart from both. A saltigue is a diviner and rain-priest whose office is hereditary in certain lineages and whose training is long. What a saltigue does publicly is read the year ahead: the rains, the harvest, sickness, deaths, and dangers to the community. The office survived the Islamisation of the Serer better than most of the rest of the tradition, and saltigue are consulted today by people who are otherwise Muslim or Catholic, which tells you something about how these communities hold more than one thing at once.