When studying religion, either on your own or in university, it is helpful to recognize that there are, almost always, two types of literature associated with a religion, that is, if the religion has a written tradition.
detail of unnamed sacred Hindu texts from collection of prof Klaus Klostermaier
The two types of religious texts are 1) sacred scripture, and 2) non-sacred, but cherished, traditional writings and commentaries.
Religion and the Honest Student 