Every person's beliefs make up his inner personality and ontological reality and play a fundamental role in ensuring his worldly and otherwordly happiness in its individual and social dimensions. In the geometry of Islamic education, scholastic theology is responsible for religious education. The development of the science of scholastic theology and its growth provides the basis for an increase in people’s religious knowledge as members of a society. Scholastic theological science is a rule-oriented science; therefore, the first and fundamental step in the development and grwoth of this science is to research its rules. Re-examining the current rules of scholastic theology as well as infering and extracting new rules is an effective move in this regard, which has recently been initiated by some researchers. However, possessing scholastic theological rules, by itslef, is not enough for the growth and development of scholastic theology. One must also know how to apply these rules. Research on various functions of scholastic theological rules provides this knowledge. The present essay aimed at studying this issue with a descriptive-analytical method. The result show that scholastic theological rules have two functions of adaptation and mediation, and in relation to resolving the conflict in the inferred propositions, they have four types of functions of explanation, interpretation, preference and restriction.