Human beings have been exclusively endued with the blessing of intellect through which they can take hold of the true knowledges on whose light they can develop and attain self-perfections. However, these knowledges differ in the levels of endorsing, since some kinds of knowledge are advocated through preponderating the preferred side to the less preferred, while other kinds are advocated through the absence of any probability of the otherwise. Of this kind of advocation is termed as decisiveness on its basis all the epistemological principles are presented as the cornerstone of the other creeds and beliefs.The faiths that create themselves in the human self are the products of introductions that differ from one person to another according to one’s cultural backgrounds and the devices used in the issue. Through these devices, man can get a universal vision suitable to the power of these introductions, the scope of its control over one’s self and the result expected therefrom. In this way, they serve as a basis on which one depends in one’s practical behavior.Creed generally and the creed of monotheism particularly are the most important issues that played the most vital role in the building of the epistemological system of human lives. This creed is responsible for sketching the map of man’s progress and behavior; and on the light of it, man’s view of the world is decided. Because of the great significance of creed, it is inevitable to seek it in such a way that assures decisiveness and certainty in their terminological concepts.The writer of the essay attempts to make references to this issue through showing the definition and the different kinds of evidence in order to prove which of these kinds of evidence can lead to decisiveness and certainty in their particular senses. He also gives an adequate answer to the following critical questions: Why is it necessary to recognize the creed through certainty in its particular sense only rather than other ranks? What is the way that takes to certainty? What are the types of it? Having answered these questions, the writer focuses only on the types that are useful for proving the obligatory on the light of which the significance of evidence of inherence in argumentation, the method it helps us prove a creed and the fundaments that help us verify that creed. All these points are proven through the employment of the demonstrative and logical style, plus quoting some words of famous wise people and logicians when necessary.The writer finally concludes that the evidence of inherence plays the most vital role in proving the creeds and even stands for the one and only evidence through which certainty in its particular sense is attained to prove the existence of the Necessary Existent God and some of His Majestic Attributes.