How do you know what was his mission?
God revealed it:
"Behold, I am he who was prepared from the foundation of the world to redeem my people. Behold, I am Jesus Christ. I am the Father and the Son. In me shall all mankind have life, and that eternally, even they who shall believe on my name; and they shall become my sons and my daughters."
The brother of Jared sees the finger of the Lord as He touches sixteen stones—Christ shows His spirit body to the brother of Jared—Those who have a perfect knowledge cannot be kept from within the veil—Interpreters are provided to bring the Jaredite record to light.
www.churchofjesuschrist.org
"But behold, all things have been done in the wisdom of him who knoweth all things. Adam fell that men might be; and men are, that they might have joy. And the Messiah cometh in the fulness of time, that he may redeem the children of men from the fall. And because that they are redeemed from the fall they have become free forever, knowing good from evil; to act for themselves and not to be acted upon, save it be by the punishment of the law at the great and last day, according to the commandments which God hath given. Wherefore, men are free according to the flesh; and all things are given them which are expedient unto man. And they are free to choose liberty and eternal life, through the great Mediator of all men, or to choose captivity and death, according to the captivity and power of the devil; for he seeketh that all men might be miserable like unto himself."
Redemption comes through the Holy Messiah—Freedom of choice (agency) is essential to existence and progression—Adam fell that men might be—Men are free to choose liberty and eternal life. About 588–570 B.C.
www.churchofjesuschrist.org
"Behold I have given unto you my gospel, and this is the gospel which I have given unto you—that I came into the world to do the will of my Father, because my Father sent me. And my Father sent me that I might be lifted up upon the cross; and after that I had been lifted up upon the cross, that I might draw all men unto me, that as I have been lifted up by men even so should men be lifted up by the Father, to stand before me, to be judged of their works, whether they be good or whether they be evil—And for this cause have I been lifted up; therefore, according to the power of the Father I will draw all men unto me, that they may be judged according to their works."
Jesus commands that the Church be called in His name—His mission and atoning sacrifice constitute His gospel—Men are commanded to repent and be baptized that they may be sanctified by the Holy Ghost—They are to be even as Jesus is. About A.D. 34–35.
www.churchofjesuschrist.org
"For were it not for the redemption which he hath made for his people, which was prepared from the foundation of the world, I say unto you, were it not for this, all mankind must have perished. But behold, the bands of death shall be broken, and the Son reigneth, and hath power over the dead; therefore, he bringeth to pass the resurrection of the dead."
How Christ is both the Father and the Son—He will make intercession and bear the transgressions of His people—They and all the holy prophets are His seed—He brings to pass the Resurrection—Little children have eternal life. About 148 B.C.
www.churchofjesuschrist.org
There are other revelations I could cite, but these may be adequate to answer the question?
