Apostle Russell M. Nelson referenced a list of things the Book of Mormon is during his October 2017 General Conference address. The following is an excerpt from that list: ¹

“The Book of Mormon affirms: The individual identity of Heavenly Father and His Beloved Son, Jesus Christ.”

 

From Wikipedia, Sabellianism: ²

In Christianity, Sabellianism in the Eastern church or Patripassianism in the Western church (also known as modalism, modalistic monarchianism, or modal monarchism) is the nontrinitarian or anti-Trinitarian belief that the Heavenly Father, Resurrected Son, and Holy Spirit are three different modes or aspects of one monadic God…

Excerpts in the Book of Mormon where the with regard to the nature of the godhead reflecting a Sabellianism model: ³

Mosiah 15:
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, 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 Son—

4 And they are one God, yea, the very Eternal Father 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 yieldeth not to the temptation, but suffereth himself to be mocked, and scourged, and cast out, and disowned by his people.

 

Mosiah 16:

15 Teach them that redemption cometh through Christ the Lord, who is the very Eternal Father. Amen.

 

Alma 11:

38 Now Zeezrom saith again unto him: Is the Son of God the very Eternal Father?

39 And Amulek said unto him: Yea, he is the very Eternal Father of heaven and of earth, and all things which in them are; he is the beginning and the end, the first and the last;

 

Ether 3:

14 Behold, I am he who was prepared from the foundation of the world to redeem my people. Behold, I am Jesus Christ. I am the Father and the Son. In me shall all mankind have life, and that eternally, even they who shall believe on my name; and they shall become my sons and my daughters.

..

In the 1837 second edition of the Book of Mormon, edits were made to make it appear less Sabellian. Following are excerpts of these additions: ⁴

[added text in the 1837 version]

1 Nephi 11:18 “Behold, the virgin whom thou seest, is the mother of [the Son of] God, after the manner of the flesh.”

1 Nephi 11:21 “And the angel said unto me, behold the Lamb of God, yea, even [the Son of] the Eternal Father! Knowest thou the meaning of the tree which thy father saw?”

1 Nephi 11:32 “And it came to pass the angel spake unto me again, saying, look! And I looked and beheld the Lamb of God, that he was taken by the people; yea, [the Son of] the Everlasting God, was judged of the world; and I saw and bear record.”