Certainly, one can always devise theories which "cohere" (in the sense of "are logically consistent") which will lead one to expect known phenomena; but it is very difficult to devise a simple theory which leads you to expect the known phenomena. If you can, that is very strong evidence that the theory is true. Another example to illustrate this point is a detective story, in which the detective learns all the evidence in the opening chapters, but only solves the crime by finding, in the last chapter, a simple explanation of all that evidence; and when he has got one, he doesn't need a new prediction to render his explanation probable.There are several problems with this reasoning. First, assuming that it is true that the simplest theory that fits the evidence is the most likely true--more or less Occam's Razor--why do people think the theory that God exists is a simpler one than the theory that God does not exist? The job of explaining evidence that contradicts God's existence has gotten more and more taxing through the years, as defenders of religion have had to accomodate dinosaurs, evidence of the earth existing several billion years earlier than the Bible claims, textual evidence that the Bible had many different authors, and evidence that humans evolved from apes, whether divinely guided or not.
But the job of defending atheism has gotten easier. When opponents of evolution have pointed to difficult-to-explain phenomena like the human eye, researchers have found evidence of intermediary stages, such as ancestral creatures' proto-eyes, that makes the case against God stronger than ever. Whole universities are devoted to theological philosophy, in part because dealing logically with the existence of God is complicated; atheist philosophy dispenses much more quickly with the question of God's existence (just as it dispenses quickly with the question of other very unlikely things, like the Flying Spaghetti Monster).
But more importantly, are simple explanations necessarily better than complex ones? Jared Diamond, in Guns, Germs and Steel (see the thorough Wikipedia page), writes:
We tend to seek easy, single-factor explanations of success. For most important things, though, success actually requires avoiding many separate causes of failure.The unknown speaker of the Prospect quote might argue that too-simple explanations fail his own test too, because they cannot explain all of the effect. But his analogy to detective novels is illuminating. Detective novels, after all, are notorious for plot holes, but readers are generally happy to allow these to be papered over by an elegant, climactic explanation. (I am always irked in Harry Potter books, though, by Harry's convenient refusal to inform Dumbledore of this year's impending crisis, and then of Dumbledore's flimsy reasons for not having just revealed the whole situation to Harry.)
My father published a novel in 1974, called Easy Come, and it is a sort of anti-detective novel. It's not that the hero is an anti-hero; instead it's the author who is anti-detective-novel, actively resisting the urge to have everything come together nicely. When a clever explanation becomes available at the end of the book, the hero can't help but point out all of the incongruities that make it unsatisfying, and he wonders if the villains, who revealed their guilt by acting cornered, were actually guilty of a completely different crime, unknown to hero and author alike.
Perhaps the question of God's existence, then, really is like a detective novel--there are official explanations, which satisfy most people, but there are incongruities that bother others (even incongruities that bother atheists, such as transcendent experiences). If there is an author, he or she may have intended one explanation to be correct, but that doesn't mean the evidence supports it best, or that there is any correct explanation at all.