Fullness of the Gospel
This is used a number of ways in scripture: First, it is an explanation of what the Book of Mormon contains (see, e.g., JSH 3:3; T&C 26:7). In that sense, the term refers to a collection of prophetic testimonies about Jesus Christ as their Redeemer and guide to salvation and, in turn, Christ’s role as universal Savior and Redeemer of mankind. Second, it is a way to identify Christ revealing Himself to mankind, thereby redeeming mortals from the fall. It is in this sense that the term is used in T&C 69:3: The ascent to God is the fullness of the gospel of Jesus Christ. It shows up very early in the first chapter by Lehi. Then it is repeated by Nephi, Jacob, Enos, Mosiah, and Alma, describing their ascent experiences. It continues throughout.1 Third, the Lord has used it to describe an everlasting covenant: “…the fullness of my gospel which I have sent forth in these last days, the covenant which I have sent forth to recover my people which are of the house of Israel (T&C 23:3; 31:3; 52:1; 1 Nephi 3:4). Joseph Smith used the term in his writings and teachings at different times with different meanings. “Learning these ‘mysteries [of God]’ is the fullness of Christ’s Gospel.”2 The fullness of the Gospel consists of asking God, receiving answers, revelations, knowledge, and finally, in the Second Comforter.3
1 Preserving the Restoration, 19.
2 The Second Comforter, 11.
3 The Second Comforter, 114.