Baptism is considered the gateway ordinance to the Gospel path: "For the gate by which ye should enter is repentance and baptism by water; and then cometh a remission of your sins by fire and by the Holy Ghost" (2Nephi 31:17). It is an ordinance that God has designed to help His children start a new life as disciples of Jesus Christ. When a person is baptized, they are expressing their devotion to God and their desire to stand as His witness. When someone is baptized by a priesthood holder commissioned of Jesus Christ, they join the Church of Jesus Christ, receive a remission of their sins, and covenant to sustain His mission of both love and truth.
The purpose of baptism is beautifully explained in Mosiah 18:7-17. Here Alma teaches that when a person is baptized they covenant to "serve [the Lord] and keep his commandments". The Lord reciprocally covenants to "pour out his Spirit more abundantly upon [the person being baptized]". Before Alma baptizes Helam, he takes a moment to pray: "O Lord, pour out thy Spirit upon thy servant, that he may do this work with holiness of heart". When we are baptized we covenant to participate in God's work; God then mercifully offers us the gift of the Holy Ghost to help us fulfill that covenant. To receive the Holy Ghost we must sincerely be willing to serve the Lord and keep His commandments. When we choose to receive the Holy Ghost we are endowed with a greater capacity to act as an instrument in the hands of God to love others and teach them truth.
Why was the Savior baptized?
When Jesus approached John the Baptist to be baptized, "John forbad him, saying, I have need to be baptized of thee, and comest thou to me? And Jesus answering said unto him, Suffer it to be so now: for thus it becometh us to fulfill all righteousness" (Matt. 3:13-15).
"To fulfill all righteousness." With these four words the Savior explained why even He, the Lamb of God, even Alpha and Omega, needed to be baptized. The Lord didn't need to be cleansed from sin (for He'd never sinned), but He did need to be righteous. He needed to be baptized so that the baptismal ordinance could be sanctified unto Him for righteousness (See Doctrinal Apophenia, Pt. 2).
Joseph Smith taught: "If, then, Abel was a righteous man he had to become so by keeping the commandments; if Enoch was righteous enough to come into the presence of God, and walk with him, he must have become so by keeping his commandments, and so of every righteous person, whether it was Noah, a preacher of righteousness; Abraham, the father of the faithful; Jacob, the prevailer with God; Moses, the man who wrote of Christ, and brought forth the law by commandment, as a schoolmaster to bring men to Christ, or whether it was Jesus Christ himself, who had no need of repentance, having no sin, according to his solemn declaration to John: - now let me be baptized: for no man can enter the kingdom without obeying this ordinance: for thus it becometh us to fulfill ALL RIGHTEOUSNESS. Surely, then, if it became John and Jesus Christ, the Savior, to fulfill all righteousness to be baptized - so surely, then, it will become every other person that seeks the kingdom of heaven to go and do likewise; for he is the door, and if any person climbs up any other way, the same is a thief and a robber!" (Teachings of the Prophet Joseph Smith)
When studying the doctrine of baptism, it is essential to carefully consider the words of 2Nephi chapter 31. Here Nephi plainly teaches the doctrine of Christ, specifically focusing on the purpose of baptism. He explains that part of the reason why Jesus was baptized was to set an example for all of us to follow. But he also reveals that the Savior had a personal need to be baptized, too: "And now, if the Lamb of God, he being holy, should have need to be baptized by water, to fulfill all righteousness, O then, how much more need have we, being unholy, to be baptized, yea, even by water! And now, I would ask of you, my beloved brethren, wherein the Lamb of God did fulfill all righteousness in being baptized by water? Know ye not that he was holy? But notwithstanding he being holy, he showeth unto the children of men that, according to the flesh he humbleth himself before the Father, and witnesseth unto the Father that he would be obedient in keeping his commandments."
The baptismal covenant was the same then as it was when Alma performed baptisms in the waters of Mormon. When Jesus Christ was baptized, He also covenanted to serve God and keep His commandments. Most of these were the same commandments that you and I are asked to obey. But to Him alone was the commandment given to save the world from sin. When Jesus Christ was baptized, He covenanted with the Father to atone for our sins.
The Savior's baptism was an act of love, a message of promise, and a beautiful symbol of His mission. Similarly, the sacrament serves as a merciful ordinance of renewal for all of us that fall short of Christ's perfect standard. Though the Son of God had a perfect understanding of the doctrine of baptism when He received that ordinance, you and I did not; nor do we now. And so, each sacrament Sunday, we have the opportunity to witness unto the Father that we will be obedient in keeping His commandments according to our developing understanding. We are each a work in progress.
When I take the sacrament this Sunday, I intend to consciously participate in the ordinance with the understanding that I'm renewing my covenant to serve God and keep His commandments. By so doing, the sacrament will help point my soul to Christ. By consciously obeying the Lord's commandment to partake of the sacrament, it will be sanctified unto me for righteousness. As I do this, Satan will have less power over my heart. By aligning my obedience with my faith in Jesus Christ and His Atonement, I believe that I'll be better equipped to be an instrument in the hands of God to participate in His work of love and truth.