Well, first I’ll support what Professor Jewell says, but then go beyond it slightly, cutting through to the core. First, empiricism does not establish itself. It has to be established by a foundation that it, itself, cannot provide (a number of a priori premises).
Secondly, as even (especially) empiricists in epistemology admit, consistently applied empiricism never fully establishes anything as “true.” All they really get from empiricism alone are a series of cases (looking for a theory – or a fire). Now, if you have a theory through which to interpret empirical evidence, empirical data can – again as even (especially) empirical epistemologists accept – never conclusively establish or prove the theory. This is why they tend instead to go in for “fallsification.” Theories can be falsified empirically, but not “proven true.”
Therefore, yes, a consistent empiricist would never be able to say “there is not and never has been revelation.”
Now, I’ll also recommend this argument put forth by someone who is, himself, an atheist:
“The coolest thing about Universalism is that it has the perfect opposition. If a Christian who believes his or her faith is justified by universal reason is a Universalist, a Christian who believes his or her faith is justified by divine revelation – in other words, a “Christian” as the word is commonly used today – might be called a Revelationist.
Suppose you have two faiths. Both claim to be absolutely and undebatably true. Faith A tells you it is an ineluctable consequence of reason. Faith B tells you it is the literal word of God. Which is more likely to be accurate?
The answer is that you have no information at all. Perhaps faith B is the literal word of God, but you have no way to distinguish it from something that someone just made up. Perhaps faith A can be derived from pure reason, but you have no way to know if the derivation is accurate unless you work through it yourself. In which case, why do you need faith A?
In fact, of the two, faith A is almost certainly more powerful and dangerous. As anyone who’s majored in Marxist-Leninist Studies knows, it’s very easy to construct an edifice of pseudo-reason so vast and daunting that working through it is quite impractical. And this edifice is much more free to contradict common sense – in fact, it has an incentive to do so, because nonsensical results are especially subtle and hard to follow.
Whereas when the word of God contradicts common sense, the idea that it might not actually be the word of God isn’t too hard to come by. In other words, if faith A contains any fallacies, they are effectively camouflaged.”
Me again: A lot of so-called rational empiricists take a lot on faith themselves; they certainly don’t work through everything themselves, gathering data independently. Rather they accept from some authority this or that; they read in some book by, say, a crank like Dawkins or Dennett and pick up on some of their rhetorical flourishes and “gotcha” questions, satires, and logical fallacies/argument-from-ignorance masquerading as reason, and the like (this is much more popular among the New Atheist set, I notice, than actual reasoned argumentation). New Athiests also tend to take it on faith that scientists (physicists or what have you) have demonstrated things they haven’t really even understood properly, much less demonstrated. Und so weter. After all, believing some guy who tells you he proved the universe created itself from nothing is no more scientific than someone claiming he saw a guy turn water into wine or feed five thousand from a few loaves and fishes.
In closing, I remember a funny illustrative passage in one of the Hitchhiker’s books, on what it would truly mean to be a consistent empiricist; each day is a new day and whenever one wants to, say, use a pencil, one must experiment with it from scratch.
(Btw, none of this is to imply that looking at empirical reality has no relevance. Rather, only that empiricism by itself is incomplete and, by itself, incoherent).