The question of the existence of God is central for the seventeenth century at a time when atheism is no longer just an individual standpoint but a philosophical school and a genuine system of thought. Standing behind the new atheism of the seventeenth century was a new approach to the question of the nature of God. Scholastic thought about the existence of God was shaped in large part by Francis Suarez. Suarez begins by asking whether the existence of God falls within the domain of demonstrations in physics (the a posteriori ways of the scholastic tradition), or whether it is primarily a metaphysical question. Rene Descartes's search for an appropriate proof of God's existence goes back at least to 1630, as per a letter written by him to Mersenne. Spinoza's arguments for the existence of God are written in a Cartesian vocabulary, but they are in constant debate with Descartes's thought.