discourse and meditation

Through out the Discourse and Meditation, theres alot of questions on doubt and the existence of God. Descartes says that God is the creator of everything we see but at the same time, he kind of doubts the existence of God. How do we know he really does exist? He is known to have the superior power, no man is more powerful or perfect than God. The fact that we are able to reason, think and perceive, we exist, and our existence is devoted to God. Descartes writes alot of things that can be controversial, but the main subject that i'm concerned with throught out both the discourse and the meditations, is God's existence because Descartes argues that God is the reason for our mind and body and so on but at the same time theres doubt. How do we know whats in doubt and whats not? Theres so many questions to ask but who has the answers?