A religion (any religion) is a system of thought. A system of thought (a religion, a philosophy, a science, or simply a theory) adopts certain basic concepts (doctrines, ideas, theorems, concepts) with which it then structures the interpretation of Existence, the world, and individual phenomena.
Thus, from the outset, a system, even if it formulates an interpretation of the world, completely general, contains and produces, or can produce, all possible interpretations. In this way, it is explained that in the context of a religion, a philosophy, different schools of thought, different perceptions can be manifested historically. Thus, for example, in the context of Buddhism, which at the beginning some of its basic principles are formulated, various interpretations appear later in history. In fact, all these are deduced from the basic principles of the theory and do not belong to time, to history. Their historical formulation is completely coincidental. In the same way, all possible interpretations are extracted from the basic principles of Christianity and the various opinions that are often considered within the context of some "orthodoxy" by "any" official church as heresies are formulated historically.
Thus, religion, as a system of thought, as a worldview, is rather a way of thinking, an orientation, and not a clear and precise (with defined limits) exposition of our perception of the world. It is an open system where various and different opinions can be expressed. Thus, a religion can be a simple interpretation that as a way of thinking belongs to the first phase of religious perception - which perceives everything as a confused whole - but as a system of thought it gives the possibility to formulate perceptions that belong to higher phases of religious perception. Thus, for example, in the context of Buddhism, which at the beginning presents a completely simple and general theory of the world, interpretations that belong to the higher phases of religious perception appear afterwards. Also, in Christianity (and Islam) which religiously, typologically, belong to the fourth phase of religious perception, with the early fathers of Christianity (and the Sufis of Islam) concepts are formulated which belong to the Fifth phase of religious perception.