Jesus prayed to Heavenly Father for unity among His followers and also for unity among the people His followers taught (see John 17:11, 20–21). Christ also taught the principle of unity in the Doctrine and Covenants: “I say unto you, be one; and if ye are not one ye are not mine” (D&C 38:27).
Elder Jeffrey R. Holland compared Jesus Christ’s prayer for unity in 3 Nephi 19:20–23 with John 17:11, 20–23: “From the Savior’s language, we see clearly it is the Holy Ghost that provides such unity, a doctrinal point not so clearly communicated in the New Testament account. Furthermore, it is significant that one of the ultimate evidences God has of our belief in Deity is that we are seen and heard praying. Christ noted this evidence on behalf of the Nephites. To the Father he said, ‘Thou seest that they believe in me because thou hearest them’ [3 Nephi 19:22]. … It is the key to the miraculous manifestations of heaven and the personal companionship of the Holy Comforter(s)” (Christ and the New Covenant [1997], 280).
Elder D. Todd Christofferson of the Quorum of the Twelve Apostles explained how we may become one with the Father and the Son:
“Jesus achieved perfect unity with the Father by submitting Himself, both flesh and spirit, to the will of the Father. The Savior’s ministry was always clearly focused because there was no debilitating or distracting double-mindedness in Him. Referring to His Father, Jesus said, ‘I do always those things that please him’ [John 8:29]. …
“Surely we will not be one with God and Christ until we make Their will and interest our greatest desire. Such submissiveness is not reached in a day, but through the Holy Spirit, the Lord will tutor us if we are willing until, in process of time, it may accurately be said that He is in us as the Father is in Him. At times I tremble to consider what may be required, but I know that it is only in this perfect union that a fulness of joy can be found” (in Conference Report, Oct. 2002, 76–77; or Ensign, Nov. 2002, 72–73).