So, is Omphalos a reasonable hypothesis? I will argue here that it is not.
What Omphalos Concedes
Before we begin, it's important to note what supporters of Omphalos must concede: that there is strong evidence for an old earth. This is crucial, because it means YECs who support Omphalos acknowledge that they seem to be wrong. Everything from asteroids to ice cores to DNA points to them being incorrect: they're supposedly right only by theological technicality. Once this is admitted, the only thing standing in the way of a true old earth view is demonstrating Omphalos' many flaws. Some supporters may then retreat back to a YEC view, but this only betrays an obstinate need to preserve their beliefs whatever the cost.
Is It a Good Explanation?
There are three reasons that we should be highly suspicious of Omphalos right out of the gate. First, an Omphalos-style universe would be identical to a truly old universe. Therefore, Omphalos is unfalsifiable: it can't be disproven, so if it's wrong we would have absolutely no way of knowing it. Intellectually honest people should want to know whether they're right or wrong, and Omphalos doesn't allow for this.
The second point is almost too obvious: there's just no evidence that Omphalos is true. The only reason some Christians advocate it is so they can continue believing what they've always believed. They can't point to anything in the physical world to support Omphalos. Nor does it have any theological basis: there's nothing like this claimed anywhere in the Bible, and (as we'll see later) there's no reason for a good God to act in this way.
The third reason is based on Occam’s razor. The old earth hypothesis explains the evidence at least as well as Omphalos, but the latter requires a huge additional assumption: that it only appears old because an omnipotent deity carefully designed it that way. Thus, the "old universe" hypothesis is the better explanation.
Is the Deception Justified?
Most Christians realize intuitively that Omphalos implies deception on God’s part, and therefore reject it. It's true that God would be knowingly causing people to believe something untrue, but could he somehow be justified in doing so? I'll examine a few ways that this might be the case, and then show why they're flawed.
The first argument was used by Philip Henry Gosse in his 1857 book Omphalos, in which the hypothesis was first formally proposed. He claimed that because God created a world with mature plants, animals and humans, he could have also created the rest of the world in a "mature" form. But there's a huge difference between creating mature beings that can care for themselves and elaborately faking the evidence found in craters, fossils, tree rings and countless other sources. The former is for the clear purpose of creating a functioning world, while the latter is blatant deception carried out for no apparent reason.
Second, maybe God set things up this way to test our faith, to see if we can ignore the misleading physical evidence and find the spiritual truth. But there's no good reason to trust personal revelation over empirical evidence. We know from studying the brain and human behavior that we're highly fallible and prone to everything from poor reasoning to hallucinations. In contrast, the scientific method is a massively successful truth-finding tool—and that tool points us to an old universe. If God wants to test our faith, he can do so without resorting to deception: for example, by seeing how we react in times of trouble, or asking us to do something difficult like missionary work.
If Christians still aren't convinced, they should imagine being raised in a non-religious home and brought up with the perfectly sensible old-earth conclusion. If they were later faced with the Omphalos hypothesis, which would be more reasonable to accept? The naturalistic explanation supported by a large body of evidence, or one that says a divine being has gone to great lengths to deceive them by creating fake evidence, in the hopes that they'll somehow see through the deception? Clearly the former. So would God be justified in sending them to an eternity in hell for believing a mountain of evidence over a mere gut feeling? Clearly not.
The elaborate deception that Omphalos implies also opens up the possibility that God is deceiving us about other things as well. For instance, maybe this is all a test—but in reverse. Maybe God will send those who accept the evidence to heaven, and send those who believe dogmatically in the unfounded claims of an ancient text to hell. While this is unlikely, it's still more reasonable than the traditional Omphalos hypothesis since it gives proper weight to empirical evidence.
Finally, once Omphalos proponents have run out of options, they may appeal to omniscience and claim that God could have a good reason for his deception that we just can't comprehend. Like Omphalos itself, the appeal to omniscience is a terrible explanation: it's unfalsifiable, has no supporting evidence and violates Occam's razor. Plus, we can only hope to understand God’s motives using our human reasoning, and based on this reasoning deception would seem malevolent. To believe otherwise is to rely on blind and unquestioning faith, which would be dangerous if God did turn out to be malevolent.
As I've shown, the Omphalos hypothesis is inconsistent with a good God because it would require elaborate, unjustifiable deception that would result in eternal punishment for millions of people. I have also shown that even if Omphalos didn’t require such deception, it would still be highly suspect due to its lack of falsifiability, evidence and parsimony. Therefore, Omphalos is an unreasonable hypothesis and a poor explanation of the natural world. Once we realize that the evidence clearly points to evolution and an old universe, we should embrace it instead of grasping desperately at far-fetched alternatives.