Getting to the Premises
I recall some years back a Mormon friend boasting of an encounter he'd had with a born-again Christian. He had taken issue with the born-again's claim that just accepting Christ into your heart was enough to be saved. LDS doctrine puts a lot of emphasis on "enduring to the end", on remaining faithful, and on the dangers of even those who had been firm in the church falling into error, so the idea that a one-time choice would be enough to guarantee salvation didn't ring true with him.
"But what if someone accepts Christ, and then later goes on a murdering spree?" the Mormon had challenged the born-again.
"If he really accepted Christ, he wouldn't do that," was the other's response.
"But what if he did?"
"It would never happen. He wouldn't do it."
"But what if he did?"
My Mormon friend recounted this exchange with obvious pride, clearly very satisfied with how he had handled himself. I kept my mouth shut, but what I was thinking was: Wow. You completely lost that debate, and you don't even realize it.
It's not that I disagreed with his position, of course. This was long before my deconversion, when I still (at least ostensibly) believed the Mormon church to be true. So I agreed with his point of view. But his method of argument struck me as pointless. He wasn't addressing his interlocutor's point at all. If the born-again truly believed that someone who had accepted Christ would never afterward commit serious sins, then asking "What if he did?" is meaningless. It is (according to his worldview) not just a counterfactual, but an impossibility. You might as well ask "What if 2 plus 2 was 5?" or "What if God created a rock so big he couldn't lift it?"
Of course, though I didn't really consider this at the time, another problem with his argument is that it could be turned around just as easily to try to attack Mormonism. Mormons believe that they know the church is true because they have received a testimony through the Holy Ghost; God Himself has told them it's true. So...what if the Holy Ghost tells them it's false? Well...that wouldn't happen; they've already received a testimony that it's true; God wouldn't contradict himself. But what if He did? Well, he wouldn't. But what if He did? And so forth, and so on. It would be essentially the same argument as my friend had with the born-again...and it would be just as unproductive.
Such an argument, in fact, could be attempted against any viewpoint whatsoever...and it would be equally useless. Asking what would happen if something were true that according to the premises of the person's beliefs could not possibly be true doesn't really accomplish anything. You are--according to that person's beliefs--asking a what if about an impossibility. The question isn't provocative; it isn't damaging to the person's belief system. It is, quite simply--within the context of his worldview--completely meaningless.
Which is why I thought--and still think--that my Mormon friend had badly lost his debate with the born-again without realizing it. The born-again had stated his point of view, and all the Mormon had done was repeat what was essentially a nonsense phrase. The born-again's statement had gone unanswered and uncontested in any meaningful way, and the Mormon had just ended up spouting gibberish (within the context of the born-again's premises).
Now, what could have been a valid argument against the born-again's statement? Well, rather than ask him to consider something that couldn't possibly happen given the premises of his belief, a better tactic would have been to call into question the premises themselves. Why wouldn't a person who had accepted Christ commit a sin? He'd likely have an answer to that (my guess as to his answer: because truly accepting Christ into his heart would remove the desire for sin), but that could lead to more questions. How does he know that would remove the desire for sin? For that matter, how could you know whether or not someone had truly accepted Christ in the first place?
But of course I think there's a good reason that line of argument didn't occur to my Mormon friend. Because this, too, could be turned against Mormonism itself--and with more validity than the former method. You know the church is true because the Holy Ghost told you? Well, how do you know that "witness" really came from the Holy Ghost? A faithful Mormon would have an answer to that--something, perhaps, about how the feelings of peace that the Holy Ghost gives cannot be counterfeited by anything else--but again, the same question could be asked, how does he know that? At some level, there are premises that can be questioned. And of course, this doesn't apply just to Mormonism; it applies to any faith-based belief system.
(Of course, science has its basic premises too--the existence of cause and effect, that the laws of physics work the same everywhere, and so on. Certainly those premises aren't immune to being questioned. But on the other hand, they have a very good track record; the scientific method has made a lot of successful predictions, and led to a lot of important discoveries. So if we're asked how we know that those premises are true, we have a good answer--not, of course, that we do know, or could ever know, with absolute, 100% accuracy, but given the success of the predictions those premises have so far led to, their validity seems to have been established with a very high level of probability. The premises of faith and religion don't have that distinction.)
This is a general principle that I think important to keep in mind when considering religious claims. It's easy to ask what-ifs that seem to challenge religious beliefs, but given the premises of those beliefs, the what-ifs are easy to answer--or to dismiss as meaningless. The important thing isn't to question the consequences of the premises, but to question the premises themselves.
The real question isn't "What if". It's "How do you know".
Unfortunately, it's a question that the faithful are all too seldom willing to seriously consider...