"I bear you my testimony," a Mormon will say, "that the LDS Church is true; I know that Joseph Smith was a true prophet, and that the Church is led by a prophet today. I know that the Book of Mormon is true, that it is the word of God, and that the Book of Abraham is likewise God's word ... " Virtually every Latter-day Saint has "borne his testimony" at one time or another to family or friends, before the members of his ward, or for the benefit of someone he would like to see join the LDS Church. Mormons are encouraged to do so at every opportunity. In fact, one church service each month is regularly set aside for members to publicly share their testimonies with each other. At a very early age children are taught the basic pattern, such as using the positive term "I know" rather than what is regarded as the weaker expression "I believe."

However, is such a testimony a valid truth test? Is it a biblical truth test?

There is no reason to doubt that the majority of these testimonies are honest and sincere. But this in itself is no indication they are reliable. That portion of a testimony that pertains to things uniquely Mormon usually follows from the Latter-day Saint's exposure to an impressive presentation on a subject such as Joseph Smith's First Vision, the Book of Mormon, or the Book of Abraham. Once they are convinced by what they’ve heard, Mormons learn to regard the feeling of conviction they have as "the testimony of the Holy Ghost." Since they attribute this inner sense of “rightness” to God speaking directly to them, then they accept both the subjective feeling and what they’ve just heard, as true.  At this point, whatever they’ve been told they believe is true because they have “a testimony” of it.

The real power of a Mormon testimony, then, can actually be a potential trap that a person falls into by failing to realize that we can literally talk ourselves into anything if we want to believe it badly enough.

It is a painful fact of life, though, that sincerity is not a guarantee against being wrong. Most of us know sincere people who have been sincerely wrong. Faith must have some basis in fact. For a testimony about anything to be valid, there must be something to support it, to serve as a witness for it. Conversely, there must be nothing that legitimately discredits it.

While spiritual insight or faith is one valid measure in spiritual matters, true spiritual insight never directly contradicts valid intellectual insight or facts in the physical world. Faith may go beyond knowledge, but does not go against it. It never blatantly contradicts the facts which we perceive with our God-given common sense. Faith and fact point in a single direction. When they do not, something is seriously wrong. This is why, in spiritual matters, we are admonished to "believe not every spirit, but try the spirits whether they are of God" (I John 4:1) and to "prove all things; hold fast to that which is good" (I Thessalonians 5:21). God does not usually create faith by first offering evidence, but at some point He does provide the evidence necessary to support true faith. A Mormon believes his testimony about the Book of Mormon or the book of Abraham is supported by factual proofs, but a careful investigation shows that no such proofs exist. Instead there is overwhelming evidence against them. In the absence of valid evidence for the object of his faith, the Latter-day Saint is left with only subjective feelings, which are inconclusive. In order to be objective, one must be willing to examine the evidence both for and against religious claims.

Most Mormons cannot both objectively consider evidence that questions their point of view and maintain their subjective testimony, so few are willing to try.  As a result, even the most well-meaning, hopeful LDS testimony is invalid because it fails to wholly address truth.

This is not to say that every part of a Mormon testimony is invalid, however.

Like all honest and sincere people, Latter-day Saints have firsthand knowledge of the value of such things as loyalty, integrity, patience, thrift, modesty, a desire to know God, and of course love. All of these things make up a major share of what Mormons believe in and try to stand for. However, high standards alone do not guarantee that a particular religion is teaching the truth. Instead, we need to have a willingness to accept facts as they exist, and to learn to use them to test the views one holds, rather than falling back on subjective experience or rationalizations. This is the first step towards discovering genuine truth.