While Jesus was living on earth, was he both human and divine or did he set aside his divinity when he was born of Mary?
When topics like this come up, I usually try to find out exactly what is meant by Jesus’ divinity and what is “fully divine”. There’s something of a range of meanings that lead to different responses. Since I can’t ask clarifying questions, I’ll just have to cover the gamut.
Jesus was literally the Son of Mary and God the Father. He is the Only Begotten Son in the flesh. This gave him the ability to descend below all things and suffer more than what should be physically possible. In Gethsemane, the labors of the week weighed on Peter, James, and John and compelled them to sleep. For the Son of God, who experienced the same week and with gobs of blood dripping from his pores, the bitter cup was drunk with full consciousness. From the Annunciation through the Crucifixion, Jesus was divine because he was the Son of God.
Even before His birth, Jesus was Jehovah of the Old Testament. He created the earth and everything on it. He spoke to Moses on the mountain. He was the second member of the Godhead. His divinity was defined in His godhood. Yet he was born into this world the same as his pre-mortal brothers and sisters. D&C 93:11-13 contains a portion of the record of John testifying that Jesus was not born with a fullness of grace. “And he received not of the fulness at first, but continued from grace to grace, until he received a fulness.” Like us, he had to grow and progress. Elder Talmage taught that “Jesus was all that a boy should be, for His development was unretarded by the dragging weight of sin” (Jesus the Christ ch 9), and in that sense His progression was greater than ours. He walked the path of humanity fully human.
Additionally, Jesus’ Intercessory Prayer (John 17) makes it sound like He laid his pre-mortal divinity aside until after the triumph of the Cross. “And now, O Father,” He prays, “glorify thou me with thine own self with the glory which I had with thee before the world was” (v5). Although He maintained throughout His ministry that He was indeed Jehovah, Jesus voluntarily relinquished power, glory, and dominion to follow the laws of mortality. If His divinity is purely the identy of Jehovah, then Jesus maintained that throughout His life. If His divinity is defined by continuing in His pre-mortal duties, then we can see that the limitations of mortality prevented that.
You can see that there’s some considerations for a straight answer. In general, when those of other faiths ask if we believe that Jesus was fully divine, I found that they are usually asking if we truly believe that Jesus was the Son of God and also God. To that I answer with a direct “Yes!” and you can do the same.