This is a rather quizzical statement. Where exactly does the bible "distinguish appearance from reality"? What does it say in this regard? And what exactly is the distinction between appearance and reality? Does the bible tell its readers how they can reliably distinguish between appearance and reality? Is Bahnsen saying that appearances are not real? If we trace it further, wouldn’t this amount to saying that consciousness is not real? On the same token, did Bahnsen fully understand that there is a distinction between what we imagine and what is real? If his followers claim that he did, where did he make this distinction explicit, and why didn’t he guide his worldview accordingly?
Therefore, the Bible distinguishes appearance from reality, and it provides an ultimate conceptual framework that makes sense of the world as whole. The Biblical metaphysic affects our outlook and conclusions regarding every field of study or endeavor, and it serves as the only foundation for all disciplines from science to ethics (Prov. 1:7; Matt. 7:24-27). (Always Ready, p. 181)
Bahnsen himself was fond of referring to the first chapter of St. Paul’s Epistle to the Romans. In the first chapter, twentieth verse, the apostle writes:
The verse already dumbfounds itself by tidily encapsulating an internal contradiction. For how can something that is invisible be “clearly seen”? But add to this unworkable conundrum Bahnsen’s statement that “the Bible distinguishes appearance from reality.” How well does this statement integrate with what we read in Romans 1:20? Could it be that the “invisible things” which appear to our seeing that the apostle wanted to take as evidence of the Christian god, are merely an appearance, and not reality? Supposing the presuppositionalist proposes a method by which appearance and reality can be reliably distinguished (not that he ever will), does Paul’s epistle offer any evidence that he applied that method in order to make sure that “the invisible things” he claims “are clearly seen,” are not merely a passing appearance, but in fact are real?
For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse.
Bahnsen says that “the Bible... provides an ultimate conceptual framework that makes sense of the world as whole.” But how effectively can the bible do this when it doesn’t even have a theory of concepts, and its very foundation is built on stolen concepts? The bible clearly and incontrovertibly grants metaphysical primacy to consciousness, and yet the primacy of consciousness is false. How can one “make sense of the world as whole” when he views the world as a creation of consciousness? As a creation of consciousness, it is subject to whatever the ruling consciousness desires it to be at any given time. We can say “rocks do not sing,” but if we grant that there is a universe-creating, reality-ruling consciousness which “controls whatsoever comes to pass” (Van Til, The Defense of the Faith, p. 160), how could anyone be confident that “rocks do not sing”? Bahnsen himself asks, "He could even make the stones cry out, couldn't He?" (Always Ready, pp. 109-110) It is doubtful that he would have answered this question negatively. For all we know, the ruling consciousness could have an entire quarry of singing rocks chorusing its praises in the wilderness. The apologist has no epistemological jurisdiction here, for his own worldview’s foundations would undermine any claim to certainty on such basic things. At most he could only claim to be certain that he can never be certain (an "apparent contradiction"?), for the only prevailing standard would be absurdity as such, and nothing more.
So ironically, Bahnsen is correct when he says that “the Biblical metaphysic affects our outlook and conclusions regarding every field of study or endeavor.” Of course it would, if it is taken seriously as a truthful portrait of reality. But it does not follow from this that “it serves as the only foundation for all disciplines from science to ethics,” and it’s not unsurprising that Bahnsen gives no argument to support such a bizarre and untenable thesis.