Jesus is the Firstborn of God in the Spirit. See Col. 1:15, and Doctrine and Covenants 93:21. Jesus Christ was the un-incarnated Jehovah of the Old Testament (or the God of the Old Testament). In Exodus 3:14, Jehovah tells Moses that He is that “I Am”. Later, in John 8:58, Jesus says, “Before Abraham was, I Am. (See also 3 Nephi 11:14, Doctrine & Covenants 110:1-4). Christ was foreordained to be the Savior. See Peter 1:19-20. One of the best places you can look for answers to these questions is, The Doctrinal Exposition of the Father and the Son, by the First Presidency of the Chruch of Jesus Christ of Latter-day Saints. It has many references from the Bible, and it is an official statement from the first presidency on what Mormons believe. Here's the link: The Father and the Son - Ensign Apr. 2002 - ensign Here is a quote from there: "God is not the Father of the earth as one of the worlds in space, nor of the heavenly bodies in whole or in part, not of the inanimate objects and the plants and the animals upon the earth, in the literal sense in which He is the Father of the spirits of mankind. Therefore, scriptures that refer to God in any way as the Father of the heavens and the earth are to be understood as signifying that God is the Maker, the Organizer, the Creator of the heavens and the earth. With this meaning, as the context shows in every case, Jehovah, who is Jesus Christ the Son of Elohim, is called “the Father,” and even “the very Eternal Father of heaven and of earth” (see passages before cited and also Mosiah 16:15). With analogous meaning Jesus Christ is called “The Everlasting Father” (Isa. 9:6; compare 2 Ne. 19:6). The descriptive titles “Everlasting” and “Eternal” in the foregoing texts are synonymous. That Jesus Christ, whom we also know as Jehovah, was the executive of the Father, Elohim, in the work of creation is set forth in the book Jesus the Christ, chapter 4 [by James E. Talmage]. Jesus Christ, being the Creator, is consistently called the Father of heaven and earth in the sense explained above; and since His creations are of eternal quality He is very properly called the Eternal Father of heaven and earth." Another good link is a talk by Elder Jeffrey R. Holland, called, The Only True God and Jesus Christ Whom He Hath Sent, The Only True God and Jesus Christ Whom He Hath Sent - general-conference Christ is called the “Father of Heaven & Earth”, but never called “Father in Heaven”.
