The Son of God is known to us as Jehovah, the God of the Old Testament. He is also the God of the Nephites, the beginning and the end, the first and the last, and the very Eternal Father of heaven and of earth.
We are used to differentiating Elohim from Jehovah with the terms "Father" and "Son." To refer to the Son as "the Father" can be confusing. Nevertheless, understanding those scriptures which refer to the Jehovah as the Father will help the reader better understand the great role of our Redeemer. The doctrine is simple if you remember the three ways in which Jehovah is referred to as the Father.
First, he is referred to as the Father by virtue of divine investiture. If one is the Son of God, given all his power, authority, and grace, then one is also God and should also be referred to as "the Father." Abinadi describes it with the phrase, because he was conceived by the power of God (Mosiah 15:3). Jesus explained that He is the Father because he gave me of his fulness (DC 93:4).
Second, Christ is the Father by virtue of his role as the Creator of heaven and earth. He is, in effect, the Father of creation and therefore retains the title "the very Eternal Father of heaven and of earth." No one would argue that He created under the direction of Elohim, but if He, as a pre-mortal Spirit, could create all things in heaven and earth, then he is, indeed, the Father of Creation. Accordingly, Samuel the Lamanite prophesied of Jesus Christ, the Son of God, the Father of heaven and of earth, the Creator of all things from the beginning (Hel 14:12, italics added).
Third, Christ is the Father by virtue of his redeeming sacrifice. All those who are born again through the mighty power of the atonement become the sons and daughters of Christ. As logic would have it, this spiritual rebirth is not without parentage. The Lord, Jesus Christ, becomes the Father of our Spirits. Benjamin's people experienced this mighty change. Therefore, they were called the children of Christ, his sons, and his daughters; for behold, this day he hath spiritually begotten you; for ye say that your hearts are changed through faith on his name; therefore, ye are changed through faith on his name; therefore, ye are born of him and have become his sons and his daughters (Mosiah 5:7). As Abinadi explains the meaning of Isaiah, he repeats this doctrine, And who shall be his seed?…they whose sins he has borne; these are they for whom he has died, to redeem them from their transgressions. And now, are they not his seed? (Mosiah 15:10-12)