Matthew 3 The Baptism of Christ

Matthew 3:11. “He shall baptize you with the Holy Ghost, and with fire”

Elder David A. Bednar of the Quorum of the Twelve Apostles discussed what it means to be baptized with fire:
“Hence, as we are born again and strive to always have His Spirit to be with us, the Holy Ghost sanctifies and refines our souls as if by fire (see 2 Nephi 31:13–14, 17). Ultimately, we are to stand spotless before God” (“Clean Hands and a Pure Heart,” Ensign or Liahona, Nov. 2007, 81).

“We are commanded and instructed to so live that our fallen nature is changed through the sanctifying power of the Holy Ghost. President Marion G. Romney taught that the baptism of fire by the Holy Ghost ‘converts [us] from carnality to spirituality. It cleanses, heals, and purifies the soul. … Faith in the Lord Jesus Christ, repentance, and water baptism are all preliminary and prerequisite to it, but [the baptism of fire] is the consummation. To receive [this baptism of fire] is to have one’s garments washed in the atoning blood of Jesus Christ’ (Learning for the Eternities, comp. George J. Romney [1977], 133; see also 3 Nephi 27:19–20).

Matthew 3:16. The sign of the dove

The Prophet Joseph Smith explained that the Holy Ghost did not appear as a dove after the baptism of Jesus Christ. Rather, the descending dove signified that the Holy Ghost was present on that occasion. Joseph Smith taught:
“The sign of the dove was instituted before the creation of the world, a witness for the Holy Ghost, and the devil cannot come in the sign of a dove. The Holy Ghost is a personage, and is in the form of a personage. It does not confine itself to the form of the dove, but in sign of the dove. The Holy Ghost cannot be transformed into a dove; but the sign of a dove was given to John to signify the truth of the deed, as the dove is an emblem or token of truth and innocence” (Teachings of Presidents of the Church: Joseph Smith [2007], 81).

Matthew 3:13–17. The Father, the Son, and the Holy Ghost are three distinct and separate beings

Elder Jeffrey R. Holland of the Quorum of the Twelve Apostles explained how the members of the Godhead are one but are also separate beings:

“We believe these three divine persons constituting a single Godhead are united in purpose, in manner, in testimony, in mission. … I think it is accurate to say we believe They are one in every significant and eternal aspect imaginable except believing Them to be three persons combined in one substance, a Trinitarian notion never set forth in the scriptures because it is not true” (“The Only True God and Jesus Christ Whom He Hath Sent,” Ensign or Liahona, Nov. 2007, 40).
Elder Holland further explained that one of the reasons for confusion about the nature of the Godhead is that during the Great Apostasy, “churchmen, philosophers, and ecclesiastical dignitaries” debated the nature of the Godhead and ultimately decided that God was unknowable and incomprehensible (see “The Only True God and Jesus Christ Whom He Hath Sent,” 40–41).