"For those who live according to the flesh set their minds on the things of the flesh, but those who live according to the Spirit set their minds on the things of the Spirit. To set the mind on the flesh is death, but to set the mind on the Spirit is life and peace. For the mind that is set on the flesh is hostile to God; it does not submit to God's law, indeed it cannot; and those who are in the flesh cannot please God. But you are not in the flesh, you are in the Spirit, if in fact the Spirit of God dwells in you. Any one who does not have the Spirit of Christ does not belong to Him." (Romans 8:5-9 RSV)
The Process Of Conversion
As the verses above clearly state, no one is truly a Christian (see The Elect) without the Holy Spirit which makes conversion possible. From a Christian point of view, conversion means to turn, or change, from the world's way, that is, our own way, to God's Way. Truly change, not merely as a state of mind, but as a way of life - The Way to life, eternal life.
Repentance
Repentance is a change of mind, a vital part of conversion.
"From that time Jesus began to preach, saying, "Repent, for the kingdom of heaven is at hand." (Matthew 4:17 RSV)
"they should repent and turn to God and perform deeds worthy of their repentance." (Acts 26:20 RSV)
"As it is, I rejoice, not because you were grieved, but because you were grieved into repenting; for you felt a Godly grief, so that you suffered no loss through us. For Godly grief produces a repentance that leads to salvation and brings no regret, but worldly grief produces death. For see what earnestness this Godly grief has produced in you, what eagerness to clear yourselves, what indignation, what alarm, what longing, what zeal, what punishment! At every point you have proved yourselves guiltless in the matter." (2 Corinthians 7:9-11 RSV)
"The Lord is not slow about His promise as some count slowness, but is forbearing toward you, not wishing that any should perish, but that all should reach repentance." (2 Peter 3:9 RSV)
"unless you repent you will all likewise perish." (Luke 13:3 RSV)
Baptism
Baptism is an important act of conversion, so much so that Jesus Christ had Himself baptized by John The Baptist, not because He needed to repent of anything, but as an example to those who profess to be Christians (see Christian Living).
"John would have prevented Him, saying, "I need to be baptized by You, and do You come to me?" But Jesus answered him, "Let it be so now; for thus it is fitting for us to fulfil all righteousness." Then he consented. And when Jesus was baptized, He went up immediately from the water, and behold, the heavens were opened and He saw the Spirit of God descending like a dove, and alighting on Him; and lo, a voice from heaven, saying, "This is My beloved Son [see The Father and The Logos], with Whom I am well pleased." (Matthew 3:14-17 RSV)
"Repent, and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit." (Acts 2:38 RSV)
"Repent therefore, and turn again, that your sins may be blotted out, that times of refreshing may come from the presence of The Lord." (Acts 3:19 RSV)
"Do you not know that all of us who have been baptized into Christ Jesus were baptized into His death? We were buried therefore with Him by baptism into death, so that as Christ was raised from the dead by the glory of The Father, we too might walk in newness of life. For if we have been united with Him in a death like His, we shall certainly be united with Him in a resurrection like His [see The Last Day]. We know that our old self was crucified with Him so that the sinful body might be destroyed, and we might no longer be enslaved to sin. For he who has died is freed from sin. But if we have died with Christ, we believe that we shall also live with Him." (Romans 6:3-8 RSV)
"He who believes and is baptized will be saved; but he who does not believe will be condemned." (Mark 16:16 RSV)
The Holy Spirit
As the opening verses plainly say, "Any one who does not have the Spirit of Christ does not belong to Him." (Romans 8:9 RSV)
"In Him you also, who have heard the word of truth, the gospel of your salvation, and have believed in Him, were sealed with the promised Holy Spirit, which is the guarantee of our inheritance until we acquire possession of it, to the praise of His glory." (Ephesians 1:13-14 RSV)
"But you shall receive power when the Holy Spirit has come upon you; and you shall be My witnesses in Jerusalem and in all Judea and Samaria and to the end of the earth." (Acts 1:8 RSV) (see Bible Places)
"And we are witnesses to these things, and so is the Holy Spirit whom God has given to those who obey Him." (Acts 5:32 RSV)
"Repent, and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit. For the promise is to you and to your children and to all that are far off, every one whom The Lord our God calls to Him." And he testified with many other words and exhorted them, saying, "Save yourselves from this crooked generation." (Acts 2:38 RSV)
A Lifelong Process
Conversion is a lifelong process in which Christians are expected to "grow in the grace and knowledge of our Lord and Savior Jesus Christ" (2 Peter 3:18). Although all Christians remain sinners (e.g. Romans 7:7-25 and 1 John 1:8-10), those who know better are expected to do better.
"For He will render to every man according to his works: to those who by patience in well-doing seek for glory and honor and immortality, He will give eternal life; but for those who are factious and do not obey the truth, but obey wickedness, there will be wrath and fury." (Romans 2:6-8 RSV)
"Let your light so shine before men, that they may see your good works and give glory to your Father Who is in heaven." (Matthew 5:16 RSV)
"What does it profit, my brethren, if a man says he has faith but has not works? Can his faith save him?"
"If a brother or sister is ill-clad and in lack of daily food, and one of you says to them, "Go in peace, be warmed and filled," without giving them the things needed for the body, what does it profit? So faith by itself, if it has no works, is dead."
"But some one will say, "You have faith and I have works." Show me your faith apart from your works, and I by my works will show you my faith."
"You believe that God is one; you do well. Even the demons believe - and shudder."
"Do you want to be shown, you shallow man, that faith apart from works is barren? Was not Abraham [see Abraham, Man Of Faith] our father justified by works, when he offered his son Isaac upon the altar? You see that faith was active along with his works, and faith was completed by works, and the scripture was fulfilled which says, "Abraham believed God, and it was reckoned to him as righteousness"; and he was called the friend of God."
"You see that a man is justified by works and not by faith alone."
"And in the same way was not also Rahab the harlot justified by works when she received the messengers and sent them out another way? For as the body apart from the spirit is dead, so faith apart from works is dead." (James 2:14-26 RSV)
Fact Finder: What is sin? See What Is Sin? and The Ten Commandments and The Ten Commandments Now?