Clear and detailed prophecy

Yea, even six hundred years from the time that my father left Jerusalem, a prophet would the Lord God raise up among the Jews—even a Messiah, or, in other words, a Savior of the world.

…Wherefore, all mankind were in a lost and in a fallen state, and ever would be save they should rely on this Redeemer.

1 Nephi 10:4,6

The prophecies concerning Christ were important enough that they had sufficient detail so that the people would know what they were seeing. Included was the assurance that all people needed the Savior.

And he spake also concerning a prophet who should come before the Messiah, to prepare the way of the Lord—

… And after he had baptized the Messiah with water, he should behold and bear record that he had baptized the Lamb of God, who should take away the sins of the world.

And it came to pass after my father had spoken these words he spake unto my brethren concerning the gospel which should be preached among the Jews, and also concerning the dwindling of the Jews in unbelief. And after they had slain the Messiah, who should come, and after he had been slain he should rise from the dead, and should make himself manifest, by the Holy Ghost, unto the Gentiles.

1 Nephi 10:7,10-11