This is a non-falsifiable question but by the definitions of fact and truth then yes naturalism is the truth as it is purely based off of facts and provable laws and theories.
the quality or state of being true.
"he had to accept the truth of her accusation"
synonyms: veracity, truthfulness, verity, sincerity, candor, honesty; More
that which is true or in accordance with fact or reality.
Noun: the truth
"tell me the truth"
synonyms: what actually happened, the case, so; More
a fact or belief that is accepted as true.
Plural noun: truths
"the emergence of scientific truths"
synonyms: fact, verity, certainty, certitude; More
a thing that is indisputably the case.
"she lacks political experience—a fact that becomes clear when she appears in public"
synonyms: reality, actuality, certainty; More
used in discussing the significance of something that is the case.
Noun: the fact that
"the real problem facing them is the fact that their funds are being cut"
a piece of information used as evidence or as part of a report or news article.
Synonyms: detail, piece of information, particular, item, specific, element, point, factor, feature, characteristic, ingredient, circumstance, aspect, facet; information
"every fact was double-checked"
Naturalism is the view that nothing exists beyond the natural world and that only physical laws operate in our world, i.e. that also humans are purely physical beings. Let us suppose the naturalist wants to defend the position that naturalism is true.
Yet under naturalism every thought, just like everything else, is physically determined. Some propose that freedom of thought might be a result of 'emerging complexity', but this is based on a misunderstanding of the concept. While emergence results in phenomena that could not be predicted from the basic components of the system on their own, it never violates the physical laws by which these basic components operate. Such a violation would have to occur if free thought could be the result of purely physical processes, which are either deterministic or, at the quantum level, random on a probabilistic basis (yet significant quantum level influence on thought is not feasible under naturalism, since it would just produce random thoughts).
These circuits were shaped by evolution – yet evolution is of no help to reliably arrive at the claim that naturalism is true. Already Darwin recognized the problem that natural selection may not suffice to explain the human mind's capacity for recognition of truth and objective thought – evolution selects only for physical adaptation and behavior, not for correctness of beliefs *). When evolutionary scientists claim that religion was selected for its behavioral survival advantage, they in fact concede, if they adhere to a naturalistic worldview, that evolution can indirectly select for an allegedly false belief. So there is no use in saying that, in terms of frameworks of beliefs, evolution probably has endowed us with a reliable ability to see that naturalism – an abstract concept far beyond everyday sensory experiences – is true, and therefore we ‘ought’ to see the truth of naturalism even under determinism.
However, even if evolution could accomplish the creation of reliable logical circuitry (which is debatable), an informed decision for or against naturalism is not solely a matter of simple and straightforward logic based on premises that should be self-evident to everyone.
How then can the naturalist nonetheless assert that naturalism is true and its acceptance rational? S/he considered the evidence, s/he will reply. Yet under naturalism the brain determines how to interpret the evidence – you have no say in that. So the naturalist's brain determined that naturalism is true, and mine determined, considering the evidence as well, that naturalism is not true. Now, which brain is right? If the naturalist's acceptance of naturalism is solely dependent on the firing of his/her neurons over which s/he has no control (under determinism), then it is not possible for him/her to know that his/her brain is right and that naturalism is true. Thus under naturalism the claim that naturalism is true becomes incoherent and self-contradictory. Naturalism defeats itself.
Alvin Plantinga, Professor Emeritus of Philosophy at Notre Dame, and a Christian, has become a well-known critic of naturalism. He suggests, in his evolutionary argument against naturalism, that the probability that evolution has produced humans with reliable true beliefs, is low or inscrutable, unless their evolution was guided (for example, by God). According to David Kahan of the University of Glasgow, in order to understand how beliefs are warranted, a justification must be found in the context of supernatural theism, as in Plantinga's epistemology.
Take philosophical naturalism to be the belief that there aren't any supernatural entities - no such person as God, for example, but also no other supernatural entities, and nothing at all like God. My claim was that naturalism and contemporary evolutionary theory are at serious odds with one another - and this despite the fact that the latter is ordinarily thought to be one of the main pillars supporting the edifice of the former. (Of course I am not attacking the theory of evolution, or anything in that neighborhood; I am instead attacking the conjunction of naturalism with the view that human beings have evolved in that way. I see no similar problems with the conjunction of theism and the idea that human beings have evolved in the way contemporary evolutionary science suggests.) More particularly, I argued that the conjunction of naturalism with the belief that we human beings have evolved in conformity with current evolutionary doctrine... Is in a certain interesting way self-defeating or self-referentially incoherent.
— Alvin Plantinga, Naturalism Defeated?: Essays on Plantinga's Evolutionary Argument Against Naturalism, "Introduction
Plantinga argues that together, naturalism and evolution provide an insurmountable "defeater for the belief that our cognitive faculties are reliable", i.E., a skeptical argument along the lines of Descartes' Evil demon or Brain in a vat