Bruce R. McConkie
"In the usual manner of speaking, the Father and the Son are two separate personages who are united as one in purpose and plan and in character and attributes. Christ is the Firstborn spirit offspring of the Father in pre-existence, the Only Begotten in the flesh. But there are three specific scriptural senses in which Christ is spoken of and known as the Father:
(1) He is the Father in the sense of being the Creator and is thus referred to as ’the Father of the heavens and of the earth, and all things that in them are.’ (Ether 4:7.)
(2) He is the Father of those who abide in his gospel. Faithful saints who receive him have power given them to become his sons. (D. & C. 39:4.) Those who are ’spiritually begotten... are born of him’; they become ’the children of Christ, his sons, and his daughters.’ (Mosiah 5:7.)
(3) He is the Father by divine investiture of authority. That is, the Father places his own name, power, authority, and Godship on the Son, and empowers him to act and speak in the first person as though he were the Father so that his words and acts become and are those of the Father. All things are truly delivered to him by his Father."
(Doctrinal New Testament Commentary, 1:468)