If you have bothered to spend more than five minutes on any Internet forum in which religion is discussed, you have probably had the unfortunate experience of interacting with an Internet New Atheist.
When they are not busy making a new Richard Dawkins meme or sharing a YouTube clip of Christopher Hitchens comparing God to a megalomaniacal North Korean dictator, New Atheists spend their time pompously yet cluelessly trumpeting their ignorance of philosophy, science, theism, theology, and even atheism itself. The unfortunate but nevertheless amusing thing about the New Atheists is that, while the sentences that ooze from their keystrokes read as hilariously witty self-parody of ignorant atheists, these same sentences are often written sincerely with the most serious of intent.
This phenomenon is readily perceptible when one sees New Atheists compare God to all sorts of inane things like the "Flying Spaghetti Monster" and the "Invisible Pink Unicorn" and so forth. It is also obvious when they smugly demand that one provide "scientific proof" that God exists, presumably promptly reclining back in their chair with their arms crossed and a smirk on their face, confident that a theist won't be able to meet such a demand.
Little do they realize that the joke is on them: their comparing God to the "Flying Spaghetti Monster," or the "Pink Unicorn," or the "Invisible Leprechaun," etc., only succeeds in revealing their ignorance. Why? Because the person who believes that God is in any way analogous to the “Flying Spaghetti Monster,” or the “Pink Unicorn,” or “Santa Claus,” or a “Celestial Teapot,” etc., either:
A) Has a concept of God dimmer than that of a child's, believing that God is literally some white-bearded super-human who inhabits a given spatio-temporal location and who is "out there" for man to find;
B) Cannot adequately distinguish between an empirical question and a non-empirical question;
C) Has a self-defeating commitment to scientism.
Let us consider each point in order. When an Internet New Atheist demands "scientific proof" of God's existence, he is at the very least guilty of A. How? Whether they realize it or not, when New Atheists demand “scientific proof” (i.e., modern scientific proof) of God's existence, they are really demanding empirical proof of God's existence. But to ask for empirical evidence that God exists is simply to assume that God is susceptible to empirical scrutiny and so to assume that God is literally a physical thing that is "out there" in space and that has a spatio-temporal location. In other words, this is simply to assume that God is literally something like a white-bearded super-human who inhabits a celestial cloud somewhere out there in the universe. As such, to ask for empirical proof of God's existence is simply to commit an egregious category error.
The person that asks for empirical proof of God's existence doesn't seem to understand what God is like. It only makes sense to ask for empirical proof of something that is material and that has a given spatio-temporal location. However, because God is not a material thing and because He lacks a spatio-temporal location, God is precisely the type of thing for which one cannot demand empirical proof. For example, suppose I were to ask you: "What is the length and width of the smell of cider?" or "How much does the color white weigh?" or "What is the color of 2 + 2?" And so forth. These questions make no sense. Similarly, the demand that one show empirical proof of God’s existence is equally incoherent because God is not the type of thing that is susceptible to empirical investigation.
As virtually all denominations of Christianity agree, God is immaterial and spaceless. In fact, the Christian God is not merely an immaterial being among others; he simply is Being itself, who is not metaphysically composite and thus is not a mixture of act and potency and thus whose non-existence is impossible, and who created and sustains all things in being.
As Edward Feser has noted (here and here), once one understands this, it becomes painfully obvious to see how this God differs from, say, the gods of the Greek pantheon, or the Nordic Gods (Odin, Thor, et al.). These are different in the following regard: Zeus, Aphrodite, Ares, Hades, Odin, Thor, Wotan, and all the rest, are material beings who inhabit a given spatio-temporal location, who undergo (at least) spatial, material, and temporal change and so are a metaphysical mixture of act and potency and so could not even in principle be either self-existent (i.e. metaphysically necessary beings) or be credited with the creation of the universe and all of contingent reality; for they are contingent themselves. Thus the gods of the ancient Greeks and the ancient Nordics are nothing more than extraordinarily powerful super-humans. And this is precisely what theists deny of the Christian God.
Consider now point B. Contemplate the following inquiries:
"How many trees are in Yosemite Valley?" Or "How many objects orbit Saturn?"
"What is 2 + 2?" Or "Is murder immoral?"
The difference between these two types of inquiries is that the former are empirical inquiries and the latter are non-empirical inquiries. The first two are empirical inquiries because they can only be answered via observation and/or experimentation. In other words, in order to find out how many trees there are in Yosemite Valley, one has to drive over to Yosemite Valley and start counting. Similarly, in order to know how many objects orbit Saturn, one would have to either build and use an extremely powerful telescope or otherwise send a spaceship or an unmanned space probe to see how many objects orbit Saturn. One cannot simply sit in his chair and a priori reason his way to the correct amount of trees in Yosemite Valley or the correct number of objects that orbit Saturn.
The latter two inquiries, on the other hand, are non-empirical inquiries because they cannot, even in principle, be answered via observation and/or experimentation. Rather, non-empirical inquiries can only be answered by the use of reason. You cannot place a moral value in a test tube, for example. You cannot mix a little bit of calcium with a little bit of boron (or whatever) and see that murder really is immoral. You cannot conduct an experiment to see whether murder is immoral or not. You can certainly conduct an experiment or observe that, say, stabbing someone will cause him to undergo extreme pain and panic but you wouldn't be entitled to say, on this information alone, that stabbing people is immoral. This is because normative claims are ultimately non-empirical in nature. And, because modern science is, by design, in the business of seeking to methodologically address empirical queries, modern science is simply not equipped to answer non-empirical questions like these. Similarly, the question "What is 2 + 2?" is not an empirical question. Empirical observation may very well be useful in aiding one to answer the question, such as when, say, a small child sees two rocks next to two other rocks and this helps him to realize that there really are four rocks in total. But the question is, at bottom, one only susceptible to reason, not empirical observation.
So, once again, when the New Atheist demands "scientific proof" that God exists, or when he compares God to a "Flying Spaghetti Monster," he is only revealing that he doesn't distinguish between empirical inquiries and non-empirical inquiries.
Point C is perhaps the most unpleasant if only because it is often difficult to explain to New Atheists that science is not the only arbiter of truth, busy as they are proclaiming it so. The most obvious way to tell that an Internet New Atheist is guilty of committing C is when, after being told that God is not the sort of thing or being who has a spatio-temporal location and after being elucidated on the difference between empirical and non-empirical inquiries, he simply digs his heels in and says something like: "Well, if you can't prove God scientifically, then he doesn't exist." This type of response should immediately send up the red flag of scientism, the view that only queries that are empirical in nature have truth-content (or otherwise that science is the only arbiter of truth). On this view, non-empirical inquiries are literally meaningless—for example, the query "Is murder immoral?" Amazingly, even the question "What is 2 + 2?" seems to be meaningless on this view if it is in fact the case that such an inquiry is non-empirical in nature and so impervious to scientific endeavor.
Considering just these points, we can, at the very least, say that scientism is much too narrow an epistemology because no rational person would ever think it is meaningless to ponder whether murder is immoral or to seek the sum of 2 + 2. Indeed, as many philosophers have pointed out, we can say something even more damning of scientism: it is patently self-defeating. For the following problem arises: how do we know that scientism is true? What observation or experiment can one make or conduct to demonstrate that the claim "only empirical queries are meaningful" is true? The question is of course a rhetorical one because there is not, even in principle, an experiment or observation available to demonstrate that such a claim is true. This is because the statement that only empirical inquiries are meaningful is a metaphysical one and so is a non-empirical claim at root, not an empirical one.
So the next time you see a comment seriously comparing God to a "Flying Spaghetti Monster" or demanding "scientific proof for God," kindly inform him, verbatim, that he is "an intellectually-challenged reprobate who either has a poor understanding of God’s nature, is incapable of distinguishing between empirical and non-empirical inquiries, is committed to a sort of self-defeating scientism, or is guilty of any combination of these charges." And then say, “take that!”
Actually, please don't.