The doctrine is simple: repentance and baptism. There are those to requirements. As Jesus presents this essential doctrine, he also gives the authority of that doctrine. This is not just Jesus’ doctrine, but it is the doctrine of the Father and the Holy Ghost. Where the earlier Book of Mormon texts have this Atoning Messiah as the Father in a symbolic way, the Father now takes on a new and separate role. The Godhead is being taught, and taught as a unified force behind the law of God.
The formula of the doctrine is equally simple: repent and be baptized and be saved, or do not repent and be baptized, and be damned. There is a very simple dichotomy. There are no multiple shades of argument. There can be no contentions. There is only salvation and damnation, and salvation hinges on the essential doctrine of repentance and baptism. Is it really this simple?
“The Book of Mormon is said to contain the fulness of the gospel (see D&C 20:9; 27:5; 35:12, 17; 42:12). Some have wondered how the Lord and his prophets could state this, when in fact the Book of Mormon contains no specific reference to such matters as eternal marriage, degrees of glory in the resurrection, vicarious work for the dead, and so forth. Again, let us focus upon what the gospel is. The Book of Mormon contains the fulness of the gospel in the sense that it teaches the doctrine of redemption—that salvation is in Christ and in him alone—and the principles of the gospel (faith, repentance, rebirth, enduring, resurrection, and judgment) more plainly and persuasively than any other book of scripture. The Book of Mormon does not necessarily contain the fulness of gospel doctrine. Rather, it is a sacred repository of eternal truth relative to the most fundamental and far-reaching doctrine of all—the doctrine of Christ (see Benson 18-19).
We have received a divine commission from our Lord to teach one another the doctrine of the kingdom (see D&C 88:77). What is it that we should teach? Above and beyond all that might be said in sermons and lessons and seminars and discussions, what should be the walk and talk of the Latter-day Saints? Simply stated, we are to teach the gospel. Our primary message, like Paul’s must be “Jesus Christ and him crucified” (1 Cor 2:2). If we have any hope of preserving the faith of our fathers among our people, of building firmly on the rock of revelation and the doctrines Joseph Smith taught, then we must ground and settle ourselves in Jesus Christ and his atoning sacrifice. We must, of course, teach all the doctrines of the gospel when it is appropriate to do so. But above all, we must see to it that “we talk of Christ, we rejoice in Christ, we preach of Christ, we prophesy of Christ, … that our children may know to what source they may look for a remission of their sins” (2 Nephi 25:26). (Robert L. Millet. “This is My Gospel.” Monte S. Nyman and Charles D. Tate, Jr., eds., Third Nephi 9-30: This Is My Gospel [Provo: BYU Religious Studies Center, 1993], 19-20.)