The issue of knowledge has put forwarded many times in Quranic verses and in general it is cited along with the issue of purification. Moreover, in many verses knowledge and purification is considered as the main aim for divine messengers to deal with. The aim in this paper is to deal with the relationship of knowledge and purification. I attempt to demonstrate the close anthropological connection between them. Of course, the term of knowledge in this research is referred to religious beliefs. The attempts is doe to display how injustice behaviors and ethical break down according to Quranic verses influence directly on cognitive aspect of human life. The writer will argue that the effect and the connection of injustice and moral illness with cognitive life of man is due to anthropological and cosmological view favored by Qur`aan. In many verses the mundane life is regarded as the place of testing and the religious beliefs are basically considered as the innate and inborn knowledge due to which the effect of non-cognitive element on knowledge is recognized. The notion of justice, therefore, might be as the main purpose of all divine messengers.