Quite the contrary, Mormonism says study it out in your mind and ask God; don't take our word for it.
The asking must be done with "true intent," not with idle curiosity. That entails a willingness to act upon the answer you receive, to repent and to change your life as God directs. Jesus said much the same thing:
14 ¶ Now about the midst of the feast Jesus went up into the temple, and taught.15 And the Jews marvelled, saying, How knoweth this man letters, having never learned?
16 Jesus answered them, and said, My doctrine is not mine, but his that sent me.
17 If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself. (John 7:14-17)
My Engineering students will tell you that buying the textbook and flipping through the pages is not enough. You must study it thoroughly and work the problems. Even that is not enough: to be an engineer, you must put into practice what you have learned.
It seems more prepostrous than any other religions I’ve ever come across, except Scientology.
Of course that is a matter of perspective. My atheist friends consider all of Christianity to be equally preposterous.
I’m not asking for something that specific. I’m asking you to define the terms used. I asked, “how is anyone to suppose that this is true?” and the answer I got is “the testimony of the Holy Ghost.” If you can’t begin to define that, you have refused to answer my question.
Allow me to answer your question with a question: How does one know that anything is true?
>> Quite the contrary, Mormonism says study it out in your mind and ask God; don’t take our word for it. <<
No, that’s just it. You say, “study these scriptures.” For what? The New Testament moves the human heart to desire what is contained within. Sure, it makes some shocking claims, but it resonates with the human heart. Then, you can ask, “sounds nice, but is it true?” And there is a well-established history of its truth. And the Old Testament to establish that the claims are the fulfillment of prophecies which existed among a people for hundreds and thousands of years without understanding them.
As for what is unique to Mormonism: The book of Mormon contains nothing which stirs my heart. True, huge chunks of the Old Testament wouldn’t be very stirring without the New Testament to fulfill it (Jeremiah, Numbers, Leviticus, and, frankly, Job). It justifies Smith’s unusual theology, but what attests to its truth?
Smith claims he had plates. Well, those would be interesting... but they can’t be seen.
Smith claims he translated from an ancient language. Well, if he had written down the ancient language, that would certainly testify on his behalf... but he didn’t
The original translations were removed, so Smith had to redo them... but he’s got an unsustantiable story as to why the details wouldn’t match.
There’s no record of anything Smith claims, and it requires believing that everything we think we know is false.
Children would giggle at the claims Smith made. (”A celestial dog appeared from the heavens and ate my homework!”)
You persistently refuse to supply me with a reason to believe the seemingly outlandish claims of the Book of Mormon and the seemingly ridiculous claims of Smith. Imagine if the apostles proclaimed Jesus had risen from the dead, but were shown a dead body, and they said, “that? O, that’s Jesus’ twin brother who was struck down for not believing.” That’s what Smith’s story is like.