All believers in Jesus Christ will agree that the apex and most important event of His mortal ministry was His Atonement. 

Latter-day Saints have a more expanded view of the atonement than a lot of Christianity as to where it took place. Most mainstream Christians will say that the atonement of Jesus Christ took place on the cross at the time of His Crucifixion. Latter-day Saints affirm the same. The prophet Nephi in the Book of Mormon saw that Jesus “was lifted up upon the cross and slain for the sins of the world” (1 Nephi 11:33) and Joseph F. Smith in the canonized explanation of his vision of the spirit world saw that there were angels preaching that “redemption had been wrought through the sacrifice of the Son of God upon the cross” (Doctrine & Covenants 138:35).

That said, Latter-day Saints also add the assertion that the atonement began in the Garden of Gethsemane.

Often overlooked by mainstream Christians, the New Testament gives us an indication that part of Christ’s intercessory work was performed in Gethsemane. About Christ, the author of the Gospel of Luke writes:

Jesus went out as usual to the Mount of Olives, and his disciples followed him. On reaching the place, he said to them, “Pray that you will not fall into temptation.” He withdrew about a stone’s throw beyond them, knelt down and prayed, “Father, if you are willing, take this cup from me; yet not my will, but yours be done.” An angel from heaven appeared to him and strengthened him. And being in anguish, he prayed more earnestly, and his sweat was like drops of blood falling to the ground (Luke 22:39–44, NIV)

Latter-day Saints interpret a verse in the Book of Mormon as prophesying this event. Mosiah 3:7 tells us that “lo, he shall suffer temptations, and pain of body, hunger, thirst, and fatigue, even more than man can suffer, except it be unto death; for behold, blood cometh from every pore, so great shall be his anguish for the wickedness and the abominations of his people.” In a revelation given to Joseph Smith, Christ reflected on His suffering in the Garden, saying it “caused myself, even God, the greatest of all, to tremble because of pain, and to bleed at every pore, and to suffer both body and spirit—and would that I might not drink the bitter cup, and shrink—nevertheless, glory be to the Father, and I partook and finished my preparations unto the children of men” (Doctrine & Covenants 19:18–19).

The biblical assertions as well as the claims from Latter-day Saint scripture should be cause for great reflection about how and why the atonement was wrought out in two different locations. Latter-day Saint emphasis on the Garden of Gethsemane is unique and exclusive and a gift to all followers of Jesus Christ who seek to understand the most important event of His mortal ministry as well as human history.