Two things work together to bring about this cleansing—the scriptural word is sanctification. First, sanctification is made possible because of Christ’s atoning sacrifice. He paid the price with his own life to meet the demands of justice. The Lord told Adam that we are sanctified by the blood of Christ (see Moses 6:59–60). It was the giving of this blood, the symbol of life (see Leviticus 17:11), which makes our sanctification possible. Second, a person is actually cleansed or purified of the terrible effects of sin by the sanctifying, cleansing, purging influence of the Holy Ghost. We are “sanctified by the reception of the Holy Ghost” (3 Nephi 27:20). Nephi wrote that when we repent and are baptized, “then cometh a remission of your sins by fire and by the Holy Ghost” (2 Nephi 31:17). Alma taught this doctrine as well (see Alma 13:12).
Immediately after teaching this doctrine of faith, repentance, baptism, and the reception of the Holy Ghost, Jesus said, “This is my gospel” (3 Nephi 27:21). Compare this to Christ’s teachings in 3 Nephi 11:31–40.