While some of his clerical opponents suggested that his proofs for God's existence are so obviously bad that they must have been designed by a devious atheist to in fact undermine the belief in God's existence, more secular-minded critics protested against Descartes's resorting to God as a deus ex machina to solve an epistemological quandary, and they questioned the propriety of relying on matters of faith in what should be a project of rational inquiry.