The Guide to the Scriptures defines “begotten” as:
To be born. To beget is to give birth, to procreate, or to call into being. In the scriptures, these words are often used to mean being born of God. Although Jesus Christ is the only child begotten of the Father in mortality, all people may be spiritually begotten of Christ by accepting him, obeying his commandments, and becoming new persons through the power of the Holy Ghost. (See Guide to the Scriptures.)
The scriptures teach that Jesus Christ was the only begotten son of God in the flesh. This means He was the only one of God’s children to have God as His earthly Father, and not just the father of his spirit. His spirit was created first, making Jesus Christ very literally our elder brother, since his spirit was born before any others.
For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. (John 3:16)
Each of us is a child of God because He created our spirits. Our physical bodies result from our earthly parents. Jesus, however, had only one earthly parent.
The Bible clearly explains the parentage of Jesus Christ. Mary, a mortal woman, is his mother, and God is His father. His Spirit, like everyone’s spirit, was created by God, but his physical, mortal body contained the DNA of both God and Mary. There is ample evidence of Jesus’ heritage as God’s own Son.
One early evidence came when Mary first learned of His impending birth. When the angel Gabriel told her she was to have a child, she said she was not yet married. The angel explained, “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)
This does not mean the Holy Ghost was Jesus’ Father. The Highest would be the highest of the Godhead (composed of God, Jesus Christ, and the Holy Ghost.) This highest being was, of course, God.
When Jesus Christ was baptized, God spoke from Heaven, saying, “This is my beloved Son, in whom I am well pleased.” This was God’s personal and public testimony that Jesus was exactly who He claimed to be-God’s Son. Later in history, Jesus and God appeared together to Joseph Smith, the first Mormon prophet in modern times. Again, God introduced Jesus to Joseph as His Son.
This duel heritage made possible many of the things Jesus did during his mortal ministry, most notably the atonement. He, like everyone else, inherited qualities from both His parents, and this gave Him both the ability to experience, and therefore understand, mortal challenges, as well as to be tested, but also to overcome death and live again.
Jeffrey R. Holland, a Mormon apostle, said, “This infinite Atonement of Christ was possible because (1) He was the only sinless man ever to live on this earth and therefore was not subject to the spiritual death resulting from sin, (2) He was the Only Begotten of the Father and therefore possessed the attributes of godhood that gave Him power over physical death, and (3) He was apparently the only one sufficiently humble and willing in the premortal council to be foreordained to that service.” (Jeffrey R. Holland, “The Grandeur of God,” Liahona, Nov 2003, 70-73)
Jesus, like other people who lived on earth, had His memories of His life before His birth, taken from Him. He had to regain it. Because He then had greater knowledge and ability in the gospel, he was tested and tried at a higher level than most. He passed each test, resisted every temptation, and endured every mortal trial placed before Him, dying as perfect as He was when He was born. As a result, He was worthy to take on our sins and atone for them.