Coggins your line of argument runs into dangerous territory.
The danger being that religion needs to be effective in a person's life. It needs to have a real, lasting effect. A Church needs to continually make its members believe that attending that Church (and paying tithing) produces a visible, real effect.
If you try to reduce Mormonism to a set of unfalsifiable (and therefore unverifiable) factoids, you are on the road to making it into nothing more than a fairytale.
The CoJCoLdS isn't based on abstract theological concepts or ancient history. It is based on the idea that God is
real. He has a physical body of
flesh and bone. He gives his followers actual power to
do things that other non-Mormons can't do. That God takes an active role in the individual lives of His followers, and the management of His Church.
But the believing LDS is faced with a contradiction between these real claims, and the uncomfortable realization that none of these so-called "real" effects can ever actually be seen. Sure, their belief is continually reinforced through a closed loop of anecdotal evidence and teary-eyed good feelings, but if even the dimmest light of questioning is focused on these so-called effects, it falls to tatters and gets swept into the dust heap of superstition unless the traditional coping mechanism of "faith before works" or numerous other excuses can be quickly invoked.
Science, in all its wisdom, has encountered similar problems in measurement, where the sample of data is too small or infrequent. In such a situation, the scope of the data must be increased, either through the size of the pool (many more samples), or the scope of time (many more years of data collection).
That idea can be applied to LDS claims as well. Sure, you may not be able to take three high priests in one afternoon and prove the existence or non-existence of "priesthood power", but what if you take 6 million Priesthood holders over 178 years? What if you take all other religions as the control group? In a micro scale, Mormonism is untestable and unverifiable, but I believe it can be examined at the macro level.
It should also be noted that making a list of a few LDS beliefs that can't be tested is not the same as proving that there are no testable LDS beliefs. Sure, we can't prove whether Jesus was resurrected or not, but have you really considered the testability of
every Mormon claim? Are you really certain that LDS don't believe anything that could be "tested" (or about which data could be collected and a testable hypothesis formed, with repeatable and falsifiable data collection subsequently carried out?)
Years ago, someone once asked how the Church would be different if it were "true" (a thought exercise to test the non-believer's expectations). These were my initial thoughts, based on the Church's claims for authority, power and God's influence:
I believe the surety of whether something is "true" or not doesn't rest on one piece of evidence or experience. The knowledge only comes piece by piece, question by question, almost like a sculptor chiseling away to reveal his masterpiece. So we don't have one experience or piece of evidence upon which we base our knowledge, we have dozens, or hundreds, or thousands. Different pieces of a puzzle that combine to make a coherent picture. (I'm just crazy with metaphors today).
So, when people ask me "what would it take", I respond that I'm not looking for one piece of evidence. I'm looking for a thousand. It should also be noted that I believe the burden of "proof" rests on the person making the claim, so I need evidence supporting the Church's claims before I will believe.
If the claims of the Book of Mormon were true, we would have every Mesoamerican researcher publishing papers saying "You know, it looks like we have a colony of Christ believing Hebrews here." And over the years, that belief would get more and more evidence, not less. There would be evidences of massive battles and wars of extinction around 400AD, metal plates with odd, Egyptian-like writing turning up in digs all over mesoamerica, and vestiges of Biblical beliefs in Adam and Eve, Noah's ark, the tower of babel, and the atonement turning up in central American murals and stelae. And the date of 33AD would be very, very notable for the huge change in population, and a consolidation of beliefs to pure, New Testament Christianity for hundreds of years over the entire proposed Book of Mormon geography. FARMS would publish article after article about how there really were horses and chariots and steel swords back then, instead of explaining why not.
God wouldn't hide Book of Mormon restoration evidences like the breastplate, sword of Laban, and Moroni's stone box.
Modern day spiritual claims would build up to an incredible "evidence"; you would see BYU conducting research breakthroughs in every field that surpass anything else in the world.
LDS artists, authors, filmmakers, and musicians would consistently amaze us with creations that surpass the skill of any gentile talent. LDS athletes would be breaking world records right and left, and BYU would have scores of championship trophies in every sport and field; with the priesthood, Holy Ghost, and "health in their navel(s) and marrow to their bones", there just wouldn't be competition.
In every field, church members would show a level of knowledge and understanding that surpasses what could be done without the "Holy Ghost".
Priesthood blessings would work more frequently than a placebo, patriarchal blessings would be more accurate than a $5 palm reading, and faithful church members would never, ever fall for medical, financial or any other kinds of scams, especially after praying about it.
When anyone says something that isn't the Truth in Church (including urban legends and Faith-Promoting Rumor's that aren't true), the whole congregation would know instantly by the spirit.
When a member of the ward is a child molester, or cheating on their spouse, they wouldn't be called to positions of authority; leaders would be especially inspired by the "spirit" to not put a child molester in charge of the blazer scouts.
Our prophets, seers, and revelators would make prophecies that are better and more accurate than Nostradamus, translate the Book of Mormon into other languages with a seer stone instead of the BYU translation department, translate the Book of Joseph so it could be added to the Pearl of Great Price where it should be, and reveal incredible knowledge that will still be consistent with science 200 years from now.
The JST would be used by every Bible scholar, because incredibly, it just gets more things right compared to the ancient manuscripts. And the JST would even be used by the Church, instead of being a footnote to the KJV. Or President Hinckley would finish the JST, and we would take the "translated correctly" part out of the Articles of Faith, because now it is translated correctly.
Official Doctrine wouldn't need to be defined after we know whether or not the Church leader was wrong. It would be clearly stated, without equivocation.