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In the Bible, in the Book of John, there is an account of Jesus teaching a man named Nicodemus, who was a Pharisee and a ruler among the Jews. Although Nicodemus must have had a thorough knowledge of Mosaic Law, he seemed to have little knowledge of the workings of the spirit.
- There was a man of the Pharisees, named Nicodemus, a ruler of the Jews:
- The same came to Jesus by night, and said unto him, Rabbi, we know that thou art a teacher come from God: for no man can do these miracles that thou doest, except God be with him.
- Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God.
- Nicodemus saith unto him, How can a man be born when he is old? can he enter the second time into his mother’s womb, and be born?
- Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God.
- That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.
- Marvel not that I said unto thee, Ye must be born again.
- The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit (John 3:1-8, emphasis added).
Nicodemus would have had some understanding of being "born of water," because the Jews practiced ritual immersion, not only for converts, but for cleansing after periods of uncleanness, and for holiday preparations. Jesus taught Nicodemus about the nature of the Spirit, or Holy Ghost, by using a play on words. The word for "wind" in Hebrew is ruach. The word for Holy Spirit is ruach hakodesh, or "holy wind." Christ alluded to the fact that spirit attracts spirit; people who have the spirit with them, follow the spirit and lean towards spiritual things.
- When you choose to follow Christ, you choose to be changed. “No man,” said President David O. McKay, “can sincerely resolve to apply to his daily life the teachings of Jesus of Nazareth without sensing a change in his own nature. The phrase ‘born again’ has a deeper significance than many people attach to it. This changed feeling may be indescribable, but it is real.” (In Conference Report, Apr. 1962, p. 7.)
- Our Lord told Nicodemus that “except a man be born again, he cannot see the kingdom of God” (John 3:3). Of these words President Spencer W. Kimball said, “This is the simple total answer to the weightiest of all questions. … To gain eternal life there must be a rebirth, a transformation.” (In Conference Report, Apr. 1958, p. 14.)
- President McKay said that Christ called for “an entire revolution” of Nicodemus’s “inner man.” “His manner of thinking, feeling, and acting with reference to spiritual things would have to undergo a fundamental and permanent change." (In Conference Report, Apr. 1960, p. 26.) 
- Now I say unto you that ye must repent, and be born again; for the Spirit saith if ye are not born again ye cannot inherit the kingdom of heaven; therefore come and be baptized unto repentance, that ye may be washed from your sins, that ye may have faith on the Lamb of God, who taketh away the sins of the world, who is mighty to save and to cleanse from all unrighteousness (Alma 7:14).
The Lord has ever required men to be born again, that they might become "new creatures," putting off the natural man and carnal man, and desiring to do good continually. Repentance and baptism are the first steps, both born of the desire to reconcile oneself with God and lay hold upon the redemptive power of the atonement of Christ. The above scripture is from the Book of Mormon, from Alma, who himself was a vile sinner. He went through bitter repentance and was truly born again:
- For, said he, I have repented of my sins, and have been redeemed of the Lord; behold I am born of the Spirit.
- And the Lord said unto me: Marvel not that all mankind, yea, men and women, all nations, kindreds, tongues and people, must be born again; yea, born of God, changed from their carnal and fallen state, to a state of righteousness, being redeemed of God, becoming his sons and daughters;
- And thus they become new creatures; and unless they do this, they can in nowise inherit the kingdom of God (Mosiah 27:24-26).
"We are instructed to 'come unto Christ, and be perfected in him, and deny [ourselves] of all ungodliness' (Moroni 10:32), to become “new creature[s]” in Christ (see 2 Corinthians 5:17), to put off 'the natural man' (Mosiah 3:19), and to experience 'a mighty change in us, or in our hearts, that we have no more disposition to do evil, but to do good continually' (Mosiah 5:2). Please note that the conversion described in these verses is mighty, not minor—a spiritual rebirth and fundamental change of what we feel and desire, what we think and do, and what we are. Indeed, the essence of the gospel of Jesus Christ entails a fundamental and permanent change in our very nature made possible through our reliance upon 'the merits, and mercy, and grace of the Holy Messiah' (2 Nephi 2:8). As we choose to follow the Master, we choose to be changed—to be spiritually reborn. 
- And now I say unto you that this is the order after which I am called, yea, to preach unto my beloved brethren, yea, and every one that dwelleth in the land; yea, to preach unto all, both old and young, both bond and free; yea, I say unto you the aged, and also the middle aged, and the rising generation; yea, to cry unto them that they must repent and be born again (Alma 5:49).
- For as sure as thou livest, behold, I have seen my Redeemer; and he shall come forth, and be born of a woman, and he shall redeem all mankind who believe on his name (Alma 19:13).
"The spiritual rebirth described in this verse typically does not occur quickly or all at once; it is an ongoing process—not a single event. Line upon line and precept upon precept, gradually and almost imperceptibly, our motives, our thoughts, our words, and our deeds become aligned with the will of God. This phase of the transformation process requires time, persistence, and patience. We begin the process of being born again through exercising faith in Christ, repenting of our sins, and being baptized by immersion for the remission of sins by one having priesthood authority.
- “Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life” (Romans 6:4).
"And after we come out of the waters of baptism, our souls need to be continuously immersed in and saturated with the truth and the light of the Savior’s gospel. Sporadic and shallow dipping in the doctrine of Christ and partial participation in His restored Church cannot produce the spiritual transformation that enables us to walk in a newness of life. Rather, fidelity to covenants, constancy of commitment, and offering our whole soul unto God are required if we are to receive the blessings of eternity.
- “I would that ye should come unto Christ, who is the Holy One of Israel, and partake of his salvation, and the power of his redemption. Yea, come unto him, and offer your whole souls as an offering unto him, and continue in fasting and praying, and endure to the end; and as the Lord liveth ye will be saved” (Omni 1:26).
"Total immersion in and saturation with the Savior’s gospel are essential steps in the process of being born again." 
"All those who humble themselves before God, and desire to be baptized, and come forth with broken hearts and contrite spirits, and witness before the church that they have truly repented of all their sins, and are willing to take upon them the name of Jesus Christ, having a determination to serve him to the end, and truly manifest by their works that they have received of the Spirit of Christ unto the remission of their sins, shall be received by baptism into his church (Doctrine and Covenants 20:37). Baptism by immersion in water is 'the introductory ordinance of the gospel, and must be followed by baptism of the Spirit in order to be complete. The full benefit of forgiveness of sin through the Savior’s Atonement begins with repentance and baptism and then expands upon receiving the Holy Ghost. As Nephi said,
- Baptism is the gate, “and then cometh a remission of your sins by fire and by the Holy Ghost (2 Nephi 31:17).
"The baptismal gate opens the way for additional covenants and blessings through priesthood and temple blessings. The transcendent gift of the Holy Ghost, along with membership in The Church of Jesus Christ of Latter-day Saints, is bestowed by confirmation, by the laying on of hands by those having priesthood authority." 
- Wherefore teach it unto your children, that all men, everywhere, must repent, or they can in nowise inherit the kingdom of God, for no unclean thing can dwell there, or dwell in his presence; for, in the language of Adam, Man of Holiness is his name, and the name of his Only Begotten is the Son of Man, even Jesus Christ, a righteous Judge, who shall come in the meridian of time.
- That by reason of transgression cometh the fall, which fall bringeth death, and inasmuch as ye were born into the world by water, and blood, and the spirit, which I have made, and so became of dust a living soul, even so ye must be born again into the kingdom of heaven, of water, and of the Spirit, and be cleansed by blood, even the blood of mine Only Begotten; that ye might be sanctified from all sin, and enjoy the words of eternal life in this world, and eternal life in the world to come, even immortal glory (Moses 6:57, 59).