This article presents a kind of unconventional attempt to show the logical and philosophical defect faced by any attempt of criticizing or even questioning the principle of causality. The main focus in this article is the attempt of David Hume, regarding its broad impact on atheists and materialists, and because it summarized all that has been said or is said about the apparent criticisms of this principle and its implications like the rejection and doubt in the proofs of divine existence. It has been shown in the article that the application of the principle of causality is a basis not only for the knowledge but also for the skepticism and for being aware of the ignorance. So, whoever apparently and verbally claims that he does not believe in this principle could never doubt or say that he doesn\\'t know, and even such a recognition would be impossible without employing the principle. Therefore, the atheistic and agnostic stances are logically invalid.