Naturalism is a philosophical concept that everything came about by natural law and has no supernatural influences, and all of the evidence should be examined by using the scientific method. Naturalism mainly focuses on ontology, which is the study of what exists within a material world, and things like spirits and poltergeists have no purpose in reality; so more than likely they are no more than superstition, but the concept would be considered if sufficient evidence was provided. Nature is reality and nothing metaphysical has ever been proven as there’s no physical evidence to observe; nothing to witness or test; no hypothesis or experiments can be constructed; thus no theory to be discussed.
As far back as the Hellenistic period in archaic Greece, schools of philosophies like Cynicism, Epicureanism, Stoicism, and Skepticism, all attempted to explain reality as natural causes and mostly rejected supernaturalism. As you’d expect as Christianity grew, and secularism became less, naturalism was deemed as a crime and anyone who even suggested it was labelled a heretic and this lasted throughout the dark ages until the scientific revolution during the Age of Enlightenment.
“When you don’t have explanation for a certain phenomenon, as a real human, you should suspend judgement, instead of concocting supernatural explanations out of ignorance and primordial fanaticism.
Naturalism is often frowned upon by theistic organisations as they refuse to consider that everything we see came about naturally as they think that anything that exists must have a designer. Yet this is no more than mere speculation as the scientific method has only ever discovered things that exist that have natural causes. No scientist of any authority has ever proven anything to have existed by divine architecture, so how can anything that’s not naturalism have any legitimate credence? Even if science has failed to supply a first cause ie: abiogenesis, there is still more evidence due to the theory of evolution to suggest that life either arrived here from extra-terrestrial origins or a natural cause as opposed to a supernatural origin. Supernaturalism simply has no reasonable arguments to support it, and however much theists make claims, they cannot provide any evidence whatsoever, yet constantly mock the idea of naturalism.
“Our public schools arbitrarily define science as explaining the world by natural processes alone. In essence, a religion of naturalism is being imposed on millions of students. They need to be taught the real nature of science, including its limitations.” – Ken Ham