In the history of thought, the effort to get rid of the religious and theological teachings of the Middle Ages, together with the Renaissance and reform movements, causes an evolution in the search and perception of reality. As a matter of fact, it is seen that the questioning about the belief in God increased in the period after the Industrial Revolution, starting with the modern period, and especially during the 19th century. One of these ideas, in which man is put in the center for the sake of independence from God and religious authorities, belongs to the German materialist Ludwig Feuerbach (1804-1872). Contrary to the innate approach of modern thought that became systematized with Descartes, Feuerbach argues that the idea of God is formed in the human mind afterwards and through experiences, and the concept of God is a manifestation and result of man's reflection of his own nature outward. Man, who thinks that he submits to God and loves him, creates a sort of external "other" imagination in order to attribute the features he wants to have but cannot have indeed. In other words, the source of man's vision and belief in God is the weakness inherent in his nature, then the search for an external existence that he can complete this weakness. By attributing the feelings or values that inherently exist in the human-human relationship, to a sacred other, man becomes alienated from himself. Thus, attributing the features that exist in him to God as another being, includes the meanings of man's alienation from himself, denial of his own self or essence. This alienation caused by religion and theology exposes the detachment of man from his own essence and nature, the desire to complete the deficient nature of his self with an absolute other who does not have this deficiency in himself. Alienation, which causes human depreciation, is a result of religious theology's assuming that man is a weak being in the face of God, an external other. Representing the transition from classical German idealism to materialism and positivism, Feuerbach continues to use Hegel's idealism and dialectic as a tool. However, by reading/interpreting it in reverse, he adopts the flow of thought towards the search for truth from the Absolute Spirit to the individuality. Hegel, in the problem of the relationship between mental objects and external objects, emphasizes that the thought corresponds to existence, and the guarantee of this is the Absolute Mind. Hegelian monistic idealism claims that the Absolute mind, which provides the unity between the mind and the external world, existed before the world. On the other hand, Feuerbach argues that general knowledge can be reached from particular minds. Because he argues that the truth can be acquired only if a path is followed from the object to the thought, not from the thought to the object. Thus, Feuerbach, who adopted the inductive method in his criticisms of religion and theology, said that atheism should essentially be real humanism and theology should actually be anthropology; therefore, he argues that the being believed to be God is actually human. Despite the claim that the belief in a perfect God is in human nature and innate, he claims that this belief arises from experiences through lifetime. God, when evaluated from an objective point of view, is nothing but a subjective and individual feeling. Theology should be replaced by anthropology and religion should be replaced by philosophy in order to ensure that people have a true understanding of religion instead of their baseless beliefs full of unrealistic speculations. Because, according to him, religion consist of nothing but love, where the human seeks his own truth in the reflection of reality that has become unreal due to theology, but can find it (his own truth) directly in relation between you and me. Thus, any union between two people through love is religion. The aim of our study is to reveal that in Feuerbach's thought, God is a result of human psychological weaknesses and deficiencies in his nature. It is emphasized that Feuerbach's philosophical background, his views on human nature and alienation are decisive in the formation of the aforementioned thought. Indeed he argues that God is a fictional being created by man, and that all the characteristics attributed to God are essentially belong to human nature. Therefore, by believing in God and glorifying him, man becomes alienated from his own nature. This shows that Feuerbach clearly adopted an anthropomorphic idea that sublimates human nature instead of a classical idea of God. However, although this approach generally includes serious criticisms of the belief principles of all holy religions, it is based on a body of humanistic principles that specifically and predominantly targets Christian theology, which claiming authoritarianism in the interpretation of belif in God and other principles of Christianity.