FairMormon is a non-profit organization dedicated to providing well-documented answers to criticisms of LDS doctrine, belief and practice.
O Livro de Mórmon/Testemunhas/Visualização de placas de ouro resultaria em morte
Pergunta: Será que Joseph Smith dizer que vendo as placas de ouro resultaria em morte?
The only first-person account—that made by Joseph Smith himself—says that it was Joseph who would be destroyed if he showed the plates to any other person unless commanded to do so by the Lord
It is claimed that Joseph Smith said that the penalty for viewing the gold plates was death, and that this was just a way for Joseph to hide the fact that the plates really didn't exist. However, the only first-person account—that made by Joseph Smith himself—says that it was Joseph who would be destroyed if he showed the plates to any other person unless commanded to do so by the Lord. Many accounts attributed to Joseph in which he is supposed to have claimed that anyone else who viewed the plates would die originated with people who were hostile to Joseph and the Church. Significantly, Emma's statement makes no mention of the alleged penalty associated with the unauthorized viewing of the plates.
Primary source: Joseph Smith's own words
Joseph Smith-History 1:42 describes the conditions under which Joseph was to handle the plates:
Again, he told me, that when I got those plates of which he had spoken—for the time that they should be obtained was not yet fulfilled—I should not show them to any person; neither the breastplate with the Urim and Thummim; only to those to whom I should be commanded to show them; if I did I should be destroyed. While he was conversing with me about the plates, the vision was opened to my mind that I could see the place where the plates were deposited, and that so clearly and distinctly that I knew the place again when I visited it. (emphasis added)
According to this, it was Joseph who risked destruction if he showed the plates to anyone unless explicitly commanded to do so by the Lord, not the person to whom he showed them.
Of course, we also have the testimony of the Three and Eight witnesses, who all viewed the plates without any threat of destruction.
The idea that God would "strike down" anyone who viewed the plates came from a hostile secondary source
Fawn Brodie claimed that Joseph told Martin Harris that God's wrath would strike him down if he examined the plates or looked at him while he was translating. This is supported by a second-hand source: Charles Anthon's statement regarding the visit of Martin Harris in Eber D. Howe's anti-Mormon book Mormonism Unvailed. Anthon stated:
I adverted once more to the roguery which had been in my opinion practised upon [Harris], and asked him what had become of the gold plates. He informed me that they were in a trunk with the large pair of spectacles. I advised him to go to a magistrate and have the trunk examined. He said the "curse of God" would come upon him should he do this. 
In the critical bookMormonism Unvailed, Peter Ingersoll and Sophia Lewis claimed that Joseph told them that anyone who viewed the plates would perish.
Peter Ingersoll was a hostile source. Here is what he claims that Joseph said to him:
...On my entering the house, I found the family at the table eating dinner. They were all anxious to know the contents of my frock. At that moment, I happened to think of what I had heard about a history found in Canada, called the golden Bible; so I very gravely told them it was the golden Bible. To my surprise, they were credulous enough to believe what I said. Accordingly I told them that I had received a commandment to let no one see it, for, says I, no man can see it with the naked eye and live. However, I offered to take out the book and show it to them, but they refuse to see it, and left the room." Now, said Jo, "I have got the damned fools fixed, and will carry out the fun." Notwithstanding, he told me he had no such book, and believed there never was any such book....(emphasis added)
Here we have a statement alleged to have been made by Joseph Smith that "no man can see it with the naked eye and live." However, we also see that, according to Peter Ingersoll, Joseph came up with the entire idea of the "golden bible" on the spur of the moment as a way to have "fun." Then he claims that Joseph confided to him that the plates didn't actually exist at all. There are so many inconsistencies between this story and the statements of numerous other witnesses that one wonders if Peter Ingersoll was the one who was having some "fun" with his audience. Ingersoll can also be discredited on his claim that Joseph made the story up on the spot, because Joseph was telling various people about his Moroni visits well before recovering the plates (see for example various Knight family recollections).
Examining the testimony of Sophia Lewis we find:
SOPHIA LEWIS, certifies that she "heard a conversation between Joseph Smith, Jr., and the Rev. James B. Roach, in which Smith called Mr. R. a d-----d fool. Smith also said in the same conversation that he (Smith) was as good as Jesus Christ;" and that she "has frequently heard Smith use profane language. She states that she heard Smith say "the Book of Plates could not be opened under penalty of death by any other person but his (Smith's) first-born, which was to be a male." She says she "was present at the birth of this child, and that it was still-born and very much deformed."(emphasis added)
Here we find that not only could the plates not be viewed by another person, but that the only person who could "open" them would be Joseph's first-born child. Sophia Lewis's testimony is suspicious however. Hezekiah M'Kune, Levi Lewis and Sophia Lewis went together to make their depositions before the justice. Their testimonies bear a remarkable similarity and contain the unique claim that Joseph claimed to be "as good as Jesus Christ." This claim is not related by any other individuals who knew the Prophet, suggesting that these three individuals planned and coordinated their story before giving their depositions. 
It is interesting to note that Emma Smith, admittedly much closer to her husband Joseph than the hostile sources previously quoted, never mentioned a penalty for viewing the plates. In fact, in an interview with her son Joseph Smith III in 1879, the following conversation was recorded:
[Joseph Smith III} Q: I should suppose that you would have uncovered the plates and examined them?
[Emma Smith Bidamon] A. I did not attempt to handle the plates, other than I have told you, nor uncover them to look at them. I was satisfied that it was the work of God, and therefore did not feel it to be necessary to do so.
Major Bidamon here suggested: Did Mr. Smith forbid your examining the plates?
[Emma] A. I do not think he did. I knew that he had them, and was not specially curious about them. I moved them from place to place on the table, as it was necessary in doing my work.
[JS III] Q. Mother, what is your belief about the authenticity, or origin, of the Book of Mormon?
[Emma] A. My belief is that the Book of Mormon is of divine authenticity - I have not the slightest doubt of it. I am satisfied that no man could have dictated the writing of the manuscripts unless he was inspired; for, when acting as his scribe, your father would dictate to me hour after hour; and when returning after meals, or after interruptions, he could at once begin where he had left off, without either seeing the manuscript or having any portion of it read to him. This was a usual thing for him to do. It would have been improbable that a learned man could do this; and, for one so ignorant and unlearned as he was, it was simply impossible.(emphasis added)
Emma, therefore, did not recall any specific threat of destruction associated with the unauthorized viewing of the plates.
- Eber D. Howe, Mormonism Unvailed (Painesville, OH, 1834), 272. (Affidavits examined)
- Eber D. Howe, Mormonism Unvailed (Painesville, OH, 1834), 235-236. (Affidavits examined)
- Eber D. Howe, Mormonism Unvailed (Painesville, OH, 1834), 269. (Affidavits examined)
- Hugh W. Nibley, Tinkling Cymbals and Sounding Brass: The Art of Telling Tales About Joseph Smith and Brigham Young (Vol. 11 of the Collected Works of Hugh Nibley), edited by David J. Whittaker, (Salt Lake City, Utah : Deseret Book Company ; Provo, Utah : Foundation for Ancient Research and Mormon Studies, 1991), 128. ISBN 0875795161. GospeLink (requires subscrip.)
- "Interview with Joseph Smith III", in Dan Vogel (editor), Early Mormon Documents (Salt Lake City, Signature Books, 1996–2003), 5 vols, 1:542.