Descartes believes that God's existence is clear and distinct. God exists because the thought of God is derived from a "completely clear and distinct" idea from within his being (which he concedes is a thinking being). Having come from distinct thoughts, the idea of God can therefore never be considered a falsity. From this very distinct idea of God comes everything else that one grasps distinctly and clearly.
He states, "From the fact that I cannot think of God not existing, it follows that existence cannot be separated from God and thus that he actually exists." (298) The existence of God is something that cannot be separated, just as we cannot separate the idea of an ocean without sand. Descartes explains that man is a finite being. The mind grasps ideas mainly through its perception of such objects. Descartes expounds that he is a thinking thing. He goes on to say that sensations and mental images exist in him as aspects of his thinking. He says that he knows definitively that he exists because he sees clearly and distinctly the composite parts that make up his entire self; therefore, anybody who says that he does not exist is making a false statement because he, as a thinking being, is able to clearly and distinctly grasp his being and thus it is true that he exists.
Descartes' idea of God is one who is distinctly and clearly infinite. As the idea of an infinite being cannot be truly fathomed by a finite mind (his mind), he nevertheless doesn't seek to understand such because he accepts that he is a finite being. He asserts that the idea of God contains everything else that one grasps clearly and distinctly, everything real and true, everything with any perfection. God possessing all qualities perfectly includes existence. God has no potential because as an infinite being he is perfect, whole and complete. Nothing can be added to that perfection. Only man has potential. God gets His existence only from Himself and owes such to no other being because He is the original cause of all things, including Himself.
Man is the very proof that God exists. Because man is imbued with a thinking mind that realizes that he gets all his powers, best of all his thinking mind, from his idea of God, then it is impossible for man not to realize that what he perceives of God clearly and distinctly in his mind is a reality, and that reality is the existence of God, a perfect being who can never deceive because by His perfect Being, God is free of defects. God, as a perfect being, is incapable of fraud and deception, two things that are caused by defects. God's existence is manifested in the way man is able to use his thinking powers to accept his limitations, and at the same time realize that someone greater than man has endowed man with the powers to think and discern clearly and distinctly the idea of a Supreme Being.
John Locke starts off his treatise with the thesis that ideas spring from two fountainheads--sensation and...