Eugene Seaich and Yong-In Spencer Shin on Mosiah 15:1-4

And now Abinadi said unto them: I would that ye should understand that God himself shall come down among the children of men, and shall redeem his people. And because he dwelleth in flesh he shall be called the Son of God, and having subjected the flesh to the will of the Father, being the Father and the Son--The Father, because he was conceived by the power of God; and the Son, because of the flesh; thus becoming the Father and Son--And they are one God, yea, the very Eternal Father of heaven and of earth. (Mosiah 15:1-4)

Eugene Seaich

The difficult passage in Mosiah (15: 1-4) says essentially the same thing [as believers’ “unity” with one another and Jesus unity with the Father in John 17:22], though it is often mistaken by those who fail to correlate it with the rest of Scripture for evidence of Joseph Smith's purported "early Trinitarianism." It begins by saying that "God himself shall come down among the children of men to redeem his people" (vs. 1). To Mosiah's audience, this can only have meant Yahweh (the God of the Old Testament); indeed, it corresponds to Isaiah's prophecies that Yahweh would one day become the Savior of Israel (43:3, 11; 45:21; 54:5; etc.), as well as to various Johannine and Pauline statements that Christ was the incarnation of the preexistent Being who created "all things" (John 1:1-3; Phil. 2:6; Col. 1:16). At the same time, it is said that this great Being was already both Father and Son (Mos. 15:2), for the Son had been preexistently filled with the Father's "glory" or "self" (John 17:5), thus "being the Father" as well as "the Son" (Mos. 15:2). Later, this "One God" would beget his presence in the mortal Jesus (vs. 3), making even Jesus of Nazareth and himself "One God" by virtue of their spiritual indwelling (Mos. 15:4; compare John's Jesus: "I am in the Father and the Father is in me ... [he] dwelleth in me ... he and I are one," John 14: 10). And since he now possessed the Father's "self," Jesus too became the "very Eternal Father of heaven and earth," whose "Eternalness" consisted of the Father's indwelling power and presence, "the same from eternity to eternity" (D&C 76:4; see also Heb. 13:8: "Jesus Christ, the same yesterday, today, and forever"). [1] Mosiah, moreover, goes on to promise that men may eventually become "Christ's seed" (15: 10-13), which in Pauline language means "joint heirs of God ... glorified together with Christ" (Rom. 8:17). Likewise, John's Jesus promises to glorify the disciples as the Father glorified him, making those who are righteous one with the Godhead (John 17:22). (Eugene Seaich, Ancient Texts and Mormonism, Volume 2--The Mormon Concept of Deity: Discovering the Roots of the Eternal Gospel in Ancient Israel and the Primitive Church [3d ed.; Salt Lake City: 2014], pp. 25-26 of PDF, comment in square bracket added for clarification)

Note for the following:

[1] Mormon Scripture strongly suggests that it is God's qualities and attributes (i.e. "the Name") which are eternal: "Man of Counsel is my name, and Endless and Eternal my name" (Moses 7:35). "Eternal life" (God's life) is therefore to be distinguished from simple immortality: "This is my glory, to bring to pass the immortality and eternal life of man" (1:39). The latter state is in fact described as exaltation (rather than salvation, D&C 132:17), because it is equivalent to godhood (vs. 20), i.e. God's kind of existence. Conversely, those who lose "eternal life" will suffer eternal damnation (D&C 19:7), not necessarily damnation without end, but damnation which is eternal in quality (vss. 6, 10-11)

Yong-In Spencer Shin

Analysis One

These words of Abinadi are a case of chiasmus (emphasis added):

And now Abinadi said unto them: I would that ye should understand

[A] God himself shall come down among the children of men, and shall redeem his people. And because he dwelleth inflesh he shall be called

               [B] the Son of God, and

                              [C] having subjected the flesh to the will of the Father,

                                             [D] being the Father and the Son—

                                                            [E] The Father, because he was conceived

                                                                           [F] by the power of God [compare with Luke 1:35];

                                                            [E] and the son, because of the flesh; thus

                                             [D] becoming the Father and the Son—And they are one God [compare with John 10:30] yea, the very Eternal Father of heaven and of earth.

                              [C] And thus the flesh becoming subject to the Spirit, or

               [B] the Son to the Father

[A] being one God, suffereth temptation, and yieldeth not to the temptation, but suffereth himself to be mocked, and scourged, and cast out, and disowned by his people.

The above chiasmus reveals that the Son shall be conceived by the power of God, which is the key message confirming what the angel Gabriel told Mary: that the son to whom she would give birth would be the Son of the Highest (God), as recorded by Luke:

And the angel answered and said unto her, The Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee: therefore, also that holy thing which shall be born of thee shall be called the Son of God. (Luke 1:35; emphasis added)

Analysis Two

[1] And now Abinadi said unto them:
I would that ye should understand that
God himself
shall come down among the children of men, and
shall redeem his people.

[2] And because he dwelleth in flesh
he shall be called the Son of God.

[Note: the prophet Abinadi taught that the Son of God is the God in flesh, and He shall redeem His people among the children of men]

and having subjected the flesh to the will of the Father,
being the Father and the Son—

[3] The Father,
because he was conceived by the power of God; and
the Son,
because of the flesh; thus
becoming the Father and the Son—

[4] And they are one God, yea,
the very Eternal Father of heaven and of earth.

[Note: “The Father” and “the Son” (two separate personages) become one entity (“the Father and the Son”) as one God. Thus, one God is a singular entity consisting of two separate personages of the Father and the Son. In this sense, one God can be thought of as a “family” in which a singular entity represents multiple people. In other words, “they are one Go” in verse 4 can be interpreted as “they are one God family or Godhead.” This confirms a statement by John “I [Jesus] and my Father are one” (John 10:30). The statement in verse 4 also shows that either one can be called the very Eternal Father of heaven, and the other the very Eternal Father of earth or both can jointly be called the very Eternal Father of heaven and of earth. This implies that Father and Son are co-creators of heaven and of earth.]

[5] And thus the flesh
becoming subject to the Spirit, or
the Son to the Father,
being one God,
suffereth temptation and
yieldth not to the temptation, but
suffereth himself to be
mocked, and
scourged, and
cast out, and
disowned
by his people.

[Note: The Son in the flesh is subject to the Father, and the Son in the Godhead (one God in verse 5) suffered the Crucifixion by his own people. The above analysis shows that “one God” in verse 4 means one entity of Deity or Godhead as a unit, but “one God” in verse 5 refers to “God himself” in verse 1, and “the Son of God” in verse 2, which is a singular God, the Son of God.] (Yong-In Spencer Shin, Plain and Precious: Finding the Fulness of the Gospel Through the Bible-Book of Mormon Connection [American Fork, Utah: Covenant Communications, Inc.: 2019], 123-25)