They worship the Sun and Thunder. (Jacques Marquette, 1669) Painted deer hide: detail of thunderbird motif. Attributed to the Illinois Indians (pre-1796)

All human societies have belief systems or ideologies that give meaning to people's lives and provide explanations for our place in the universe. Belief systems may consist, in part, of religious ideas about supernatural powers that created planet Earth and the life forms that inhabit it. They also include patterns of ritual behavior intended to create harmony between human beings and natural forces, on the one hand, and supernatural beings and supernatural forces, on the other. The world's cultures have devised a tremendous variety of belief systems, but a common thread among them is that they help maintain social order by reducing people's anxiety about life and death.

The Illinois belief system was an important part of everyday life. Instead of reserving ritual behavior for one day a week, as people commonly do in modern American society, the religious practices of the Illinois were intertwined with many aspects of day-to-day living. Hunters appealed to the spirit world for guidance in obtaining game animals; warriors sought the help of spirits when they went into battle; and people with health problems summoned special religious practitioners called shamans.

All ye who have hitherto hearkened to what the black gown has said to you, come into my cabin. I shall . . . teach you what I learned from my grandfather, and what we should believe. Leave their myths to the people who come from afar, and let us cling to our own traditions. (Unidentified elder of the Kaskaskia or Peoria tribe, 1693)

The traditional belief system began to change after the Illinois came into contact with Jacques Marquette and other French missionaries in the late 1600s. Missions were established at several of the Illinois villages, where Jesuit priests saying mass in the Miami-Illinois language attracted many converts to Christianity, especially among members of the Kaskaskia Tribe. However, some tribal elders resented the efforts of missionaries and tried to persuade people to reatin their traditional belief system.