In this study, we will try to shed light on the thoughts of a well-known personality of past centuries who has been effective in the intellectual landscape until today, where he disqualified reason and imposed strict restrictions on it, making it dependent on the senses. According to Kant, knowledge is the result of the interaction between sense perception and a priori knowledge. As a result, humans can know nothing more than appearances of material things, without getting to their essence and essentials. Therefore, these thoughts and others had various effects that carried serious consequences for the religious doctrine and the theological aspect of true philosophy. That is why the writer has set out to relate the course of effects resulting from these ideas, and to show their founding role in the phenomenon of contemporary atheism. This study concentrates on two main points: the first is the connection between the series of epistemological foundations formulated by this personality, and the second point is showing their effect on the philosophical inquiry, especially in the theological and metaphysical aspects.