The knowledge of theology and knowledge of philosophy focus on issues that are not in the realm of experience: the origin of existence and supernatural worlds are among these issues. Dealing with such issues reveals the rationality of them and their proximity in the realm of pure reason. Proving the principles of religion and proving the principles of reality, which are identical, are placed on theology and philosophy, respectively. The stability or instability of any theological and philosophical system depends on the stability and instability of the proof of these principles in that system. Only the formal and content conditions of the argument can firmly connect minds to reality. Proof, as a fact-based reasoning method, puts philosophy and theology together. Although the polemical method is not incompatible with the method of proof, in some situations, its user may be satisfied with silencing the opposite person. In a part of its history in the Islamic period, the knowledge of theology took a polemic path, and disturbed the its good adjacent with philosophy by his own method. We try to explain the conflict between theologians and philosophers of this period and end the origin of this conflict from the field of these two knowledge and their adjacent and interaction, by the sign of the philosophical and theological work of some intellectual scholars.