Not only is strong scientism false, but it is self-refuting. In addition, nothing will ever be discovered that can change this. No amount of future research or blockbuster discoveries can show that a self-refuting statement was true after all. Since the statement “Only what is testable by science can be true” will never itself be testable by science, a skeptic cannot respond by saying, “There may be no current evidence for its truth, but someday science will advance to the point of proving that it is true after all.” In other words, it is not only false and self-refuting, but it is necessarily so. No further scientific discoveries could make the statement true, so the skeptic’s response expresses a misunderstanding that the statement and others like it are necessarily false.
The irony is that strong scientism is a philosophical statement, expressing an epistemological viewpoint about science; it is not a statement of science, like “water is H2O” or “cats are mammals.” Strong scientism is a philosophical assertion that claims that philosophical assertions are neither true nor can be known; only scientific assertions can be true and known. Christians, therefore, should not be intellectually intimidated when they hear very smart people with advanced degrees sitting in positions of authority say things that are self-refuting. —JP Moreland (from, Why Strong Scientism is Self-Refuting)