A Testimony for Generations

If a Mormon were to approach with news of the salvation that Joseph Smith brought to the world when the angel Moroni appeared to him, you would certainly roll your eyes. But how do you know that Moroni didn't give him the book of Mormon? How do you know that Gabriel didn't present Muhammad with the Qur'an, while he was in a cave.

Enter the mass revelation at Sinai:

"For ask now of the days past, which were before thee, since the day that God created man upon the earth, and from the one end of heaven unto the other, whether there hath been any such thing as this great thing is, or hath been heard like it? Did ever a people hear the voice of God speaking out of the midst of the fire, as thou hast heard, and live? Or hath God assayed to go and take Him a nation from the midst of another nation, by trials, by signs, and by wonders, and by war, and by a mighty hand, and by an outstretched arm, and by great terrors, according to all that the LORD your God did for you in Egypt before thine eyes? Unto thee it was shown, that thou mightest know that the LORD, He is God; there is none else beside Him. Out of heaven He made thee to hear His voice, that He might instruct thee; and upon earth He made thee to see His great fire; and thou didst hear His words out of the midst of the fire." (Deut 4: 32-36)