No Other Option.
From the preface in "A Marvelous work and a wonder", LeGrand Richards gives a quick pep talk to the reader leaving on their mission to bring the restored gospel to a world that has lost the true message of their savior.
"When we find a home where "the son of peace be there" we should have a definite aim to visit that home once a week for at least six months. If we do that and present our message in a systematic and orderly manner, the people with either join the Church or admit the message is true, but their social and family standing will not permit their accepting it, if they have followed with interest your presentation, realizing of course, that the spring of the Lord must accompany your efforts since "the letter killeth, but the spirit giveth life" (2 Cor 3:6).
["A Marvelous work and a Wonder", Preface, Page xiii]
The son of peace obviously being a term for a person with an acceptance to hear what they have to say. But I find this statement intriguing because LeGrand has stated here that if an LDS missionary can reason properly, the potential hearer has no other option but to accept the Mormon "truth".
However, an honest review of the facts of Mormon history, archaeological evidence, the translation of the book of Abraham, contradictions of the Bible with the book of Mormon and even the very nature of God; show that a systematic and orderly review of Joseph Smith's revelations in the 1820s and '30s leaves more questions and holes than such a solid position that Richards professes.
If the Mormon Gospel truly is inspired of God, it would be completely bulletproof. Truth must exist outside of feelings or experiences.
When a missionary comes knocking, this is the perfect opportunity to engage with them, hear them, and lovingly show them the truth about what they really believe. A critical examination of "A marvelous work and wonder" shows how the Gospel of Jesus of the Bible is not consistent with Joseph Smith's revelations, and are incompatible with each other.
After examination, either one is right or they're both wrong, and the willingness to come to one of those options must be an option. As even President Ruben J. Clark said:
“If we have the truth, it cannot be harmed by investigation. If we have not the truth, it ought to be harmed.”
At the end of the day, a gospel without the true Jesus cannot save.