First Preliminary: The Criterion for Knowing

Discussing the criterion for knowing in general, and the criterion for knowing Islam in particular, requires presenting some preliminaries:

1. The Necessity of the Criterion for Knowing

To know anything in the world, a criterion is needed, and knowing Islam is no exception to this rule. What is meant by knowing is distinguishing one thing from another, such as distinguishing good from evil, the truth from falsehood, or right from wrong, and this is possible when there is a criterion for distinction. It is clear that judgment is impossible without a criterion, and even if it were possible, each person would judge differently, which would ultimately make judgment impossible; because without a criterion, one cannot distinguish between correct and incorrect judgments. The discord among Muslims, which has led to their weakness and the strength of their enemies, might stem from their lack of a criterion for knowing or their failure to adhere to it, and this makes the need for such a criterion and adherence to it even clearer.

2. The Unity of the Criterion for Knowing

The discord among Muslims is caused by their differing understandings of Islam; that is, different individuals and groups of Muslims have different understandings of Islam and do not tolerate the understandings of others about it. Clearly, this discord cannot be resolved without achieving a single understanding, and to achieve a single understanding, there must be a single criterion.