One of the most disputed doctrines of Christianity involves the characteristics of God and the other members of the Godhead. Because of certain statements in the New Testament indicating that members of the Godhead are one, some theologians have taught that the members of the Godhead are one in substance. However, a careful reading of the New Testament indicates this is not the meaning. For example, in his great prayer of supplication, the Savior prays to the Father for his chosen disciples and then adds: "Neither pray I for these alone, but for them also which shall believe on me through their word; That they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me. And the glory which thou gavest me I have given them; that they may be one, even as we are one." (John 17:20-22. Italics added.)
It is clear from this scripture that the Savior is not praying for the people to become one in substance with him and the Father. This statement is further clarified by the Savior in the Book of Mormon where he indicates again that he is praying for all those who will believe on him. Then he adds: "Father, I pray not for the world, but for those whom thou hast given me out of the world, because of their faith, that they may be purified in me, . . . that I may be glorified in them." (3 Nephi 19:29.)
Thus the way we may become one with the Father and the Son is to keep the commandments of the Lord so that we might be sanctified or purified and be worthy to have their presence with us.