Jehovah
Jehovah — the covenant name, 'I AM', the premortal Christ
And as sure as the Lord liveth, so sure as many as believed, or as many as were brought to the knowledge of the truth, through the preaching of Ammon and his brethren, according to the spirit of revelation and of prophecy, and the power of God working miracles in them—yea, I say unto you, as the Lord liveth, as many of the Lamanites as believed in their preaching, and were converted unto the Lord, never did fall away. Alma 23:6
Mormon swears 'as the Lord liveth' that every Lamanite truly converted 'unto the Lord' stayed faithful. The Lord they turned to is the Christ that Aaron and Ammon preached (Alma 21:9; 22:13-14), so conversion here means lasting conversion to Him.
How we know: Jehovah is the premortal Christ (Abraham 1:16; D&C 110:3–4)
- the same title in Alma 22:13-14 — What Aaron taught the king who then 'had been converted unto the Lord' (Alma 23:3): redemption through Christ.