The belief that God or gods exist is usually called theism. People who reject belief that God or any deities exist are called atheists. Agnostics think we cannot know for sure whether God or gods exist, but still might (or might not) believe at least one deity exists. People who believe in God but not in traditional religions are called "deists". People who believe that the definition of ""God"" should be defined before taking a theological position are ignostic.