Introduction to the Gospel, pg. 312; “Joseph Smith became a prophet and spokesman for God, a living witness of the principle of continuous revelation which characterized God’s relationship to man…In the restoration, man was raised to the dignity which he had formerly known both in the Hebrew and Christian scripture. Original sin and human depravity were done away with and in their place came again Jesus’ high regard for the dignity of man, the worth of every individual as a child of God, and great emphasis on man’s freedom and accompanying moral responsibility…in the Latter-day Saint teaching of salvation which reveals a fine balance between the grace of Deity and man’s individual merit.” – Lowell Bennion
John 2:24-25; “But Jesus did not commit himself unto them, because he knew all men, 25 And needed not that any should testify of man: for he knew what was in man.”
Both Jews and Christians have always believed in original sin, thus the need for a sacrifice for our sins.