Their main religious text, The Book of Mormon states that by following an experiment, one can supposedly prove the book's "divinity".
The "reason" this deity is supposed to give the performer of the experiment is supposed to be some sort of "revelation" from a "Holy Ghost" deity.
If this experiment does not work, then an individual has a perfect proof that at least all the parts of the book explicitly tied to the experiment are in fact not devine. The CJCLDS would have serious difficulty explaining why such an individual should join and practice the religion. Hypothetically, there would be no better way to honestly get rid of door to door, "tracting" CJCLDS missionaries from one's doorstep.