On the contrary it is quite certain that his cosmology, though strongly influenced by «On Mathematical Concepts of the Material World,» was still a «free creation of the human mind.» (religion-online.org)
You can say that both «demonic activity» and «hellfire» are simply creations of the human mind. (religion.blogs.cnn.com)
«In the face of this fact, very simple logic and rationale dictates that the notions you subscribe to are the religious creations of the human mind, and not absolute truth.» (religion.blogs.cnn.com)