This present study is related to explaining of Descartes about human spirit using his logical demonstration; Descartes tries to describe one of the principal contexts in his writings, in fact, confirmation of existence origin. The reasons that he presents are not theological.
In his opinion, belief in God in human is natural, and it is arising from his tendency to idealism. In his view, God is an infinite substance. Although he presents a mechanical explanation from material universe, but his cordial belief guide him to a spiritual surrender and a deep tranquility against the will of God.