In Things Fall Apart, the Igbo people are deeply religious and follow their customs and traditions very strictly. One of these religious customs is to consult Oracles when any major decision needs to be made by the tribe. They use different Oracles for different matters, and they believe that the Oracles act as a kind of liaison between them and their gods. One example of this is when they have to make a decision about whether to go to war with a neighboring tribe. Achebe writes that the people of Umuofia (the village in which the characters in the novel live) “never went to war unless its case was clear and just and was accepted as such by its Oracle--the Oracle of the Hills and Caves.” It is not enough for the people themselves to determine whether a war is justified; they have to make sure it is approved by the Oracle, or they could risk some kind of punishment.
Whether they are unique in their use of Oracles is a matter of interpretation, but many would say that they are not unique. While it is true that this is part of what causes the Igbo people to clash so greatly with the Christians who arrive and try to convert the Igbo, it is also not very different in theory from what many other religions do. It is not uncommon for certain religions, even today, to use some sort of mediator to act as a messenger between the people and a God or gods. In fact, the use of Oracles goes back even to ancient Greece and can be seen represented in plays like Oedipus Rex by Sophocles, where men would go and seek out Oracles to find out their fate and determine how to act from there.