[Quester]

It is not the prophet, who is only a tool, ... but the revelation.

It is not Moses, but rather ... God's revelation which came through Moses.

Since the gospel (i.e. God's revelation regarding THE WAY of our entry into the His Kingdom) was established, at least, by the time of Paul's writing, some 1900+ years ago, as unchanging per Galatians 1:8,9 ...

... what revelation does Joseph bring to this dispensation which is, somehow, necessary to the question of our salvation ?

[Grig]

"Since the gospel (i.e. God's revelation regarding THE WAY of our entry into the His Kingdom) was established, at least, by the time of Paul's writing, some 1900+ years ago, as unchanging per Galatians 1:8,9 ... what revelation does Joseph bring to this dispensation which is, somehow, necessary to the question of our salvation ?"

The gospel is unchanging, true, but man's understanding of it has evolved away from the truth, and the authority of God was lost. A prophet was required to restore the fullness of the gospel and the authority. There was much knowledge that had to be restored, and what little of it you already know of you clearly reject. If you want to konw more, search on 'restoration' on lds.org