conversion

Concise Bible Dictionary:

This is from ἐπιστρέθω, “to turn to.” It is in scripture the real effect that accompanies the new birth, a turning to God. It is beautifully expressed in the case of the Thessalonians, showing how they “turned to [the same word] God from idols, to serve the living and true God” (1 Thess. 1:99For they themselves show of us what manner of entering in we had unto you, and how ye turned to God from idols to serve the living and true God; (1 Thessalonians 1:9)). Paul and Barnabas were able to make known to the saints the “conversion of the Gentiles” (Acts 15:33And being brought on their way by the church, they passed through Phenice and Samaria, declaring the conversion of the Gentiles: and they caused great joy unto all the brethren. (Acts 15:3)). In Peter’s address to the Jews he said, “Repent ye therefore, and be converted, that your sins may be blotted out” (Acts 3:1919Repent ye therefore, and be converted, that your sins may be blotted out, when the times of refreshing shall come from the presence of the Lord; (Acts 3:19)). Without being converted they could not enter the kingdom of heaven (Matt. 18:33And said, Verily I say unto you, Except ye be converted, and become as little children, ye shall not enter into the kingdom of heaven. (Matthew 18:3)). The word is used in a somewhat different sense in respect to Peter himself. The Lord, knowing that he would fall under the sifting of Satan, said, “When thou art converted strengthen thy brethren”; that is, when he had returned in contrition, or been restored. In the Old Testament the Hebrew words signify the same, “to be turned,” “to turn back” (Psa. 51:1313Then will I teach transgressors thy ways; and sinners shall be converted unto thee. (Psalm 51:13); Isa. 6:1010Make the heart of this people fat, and make their ears heavy, and shut their eyes; lest they see with their eyes, and hear with their ears, and understand with their heart, and convert, and be healed. (Isaiah 6:10); Isa. 60:55Then thou shalt see, and flow together, and thine heart shall fear, and be enlarged; because the abundance of the sea shall be converted unto thee, the forces of the Gentiles shall come unto thee. (Isaiah 60:5); compare Isa. 1:2727Zion shall be redeemed with judgment, and her converts with righteousness. (Isaiah 1:27), margin).

Strong’s Dictionary of Greek Words:

Greek:
ἐπιστροφή
Transliteration:
epistrophe
Phonic:
ep-is-trof-ay’
Meaning:
from 1994; reversion, i.e. morally, revolution
KJV Usage:
conversion

From Anstey’s Doctrinal Definitions:

This refers to a person’s heart being turned toward God (Psa. 19:7; 51:137The law of the Lord is perfect, converting the soul: the testimony of the Lord is sure, making wise the simple. (Psalm 19:7)
13Then will I teach transgressors thy ways; and sinners shall be converted unto thee. (Psalm 51:13)
; Jer. 31:1818I have surely heard Ephraim bemoaning himself thus; Thou hast chastised me, and I was chastised, as a bullock unaccustomed to the yoke: turn thou me, and I shall be turned; for thou art the Lord my God. (Jeremiah 31:18); Ezek. 33:1111Say unto them, As I live, saith the Lord God, I have no pleasure in the death of the wicked; but that the wicked turn from his way and live: turn ye, turn ye from your evil ways; for why will ye die, O house of Israel? (Ezekiel 33:11); Luke 1:1616And many of the children of Israel shall he turn to the Lord their God. (Luke 1:16)). Initially, conversion occurs when a person is born of God (Matt. 18:33And said, Verily I say unto you, Except ye be converted, and become as little children, ye shall not enter into the kingdom of heaven. (Matthew 18:3); Acts 3:19; 15:3; 26:1819Repent ye therefore, and be converted, that your sins may be blotted out, when the times of refreshing shall come from the presence of the Lord; (Acts 3:19)
3And being brought on their way by the church, they passed through Phenice and Samaria, declaring the conversion of the Gentiles: and they caused great joy unto all the brethren. (Acts 15:3)
18To open their eyes, and to turn them from darkness to light, and from the power of Satan unto God, that they may receive forgiveness of sins, and inheritance among them which are sanctified by faith that is in me. (Acts 26:18)
; 1 Thess. 1:99For they themselves show of us what manner of entering in we had unto you, and how ye turned to God from idols to serve the living and true God; (1 Thessalonians 1:9), etc.), but it is not used exclusively for a person’s new birth and salvation, as many think. If, at some time later in a believer’s life, he were to become careless in his walk and turn to the world, he would need to be converted again. Hence, it is possible for someone to be converted more than once—but it is a sad thing indeed if he should require subsequent conversions. This does not mean that if a believer fails, he loses his salvation and needs to get saved all over again, but rather, that he needs his heart turned back to the Lord for the restoration of his communion with God.
W. Kelly said, “Scripture uses it [conversion] not merely for the first turning to God, but for a turning again to Him if one has slipped away. This is really the main distinction between conversion and quickening. For quickening can only be once, but conversion may be repeated” (Lectures Introductory to the Study of the Minor Prophets, p. 378).
James said, "Brethren, if any of you do err from the truth, and one convert him; let him know that he which converteth a sinner from the error of his way shall save a soul from death, and shall hide a multitude of sins" (James 5:19-2019Brethren, if any of you do err from the truth, and one convert him; 20Let him know, that he which converteth the sinner from the error of his way shall save a soul from death, and shall hide a multitude of sins. (James 5:19‑20)). By saying, "Brethren, if any of you..." it is clear that James was referring to believers. Real believers can "err from the truth" and fail, and if they do, they need to be converted again. The "death" that James speaks of here is physical death, which God might allow in a wayward believer's life as a governmental judgment, if he does not repent (1 John 5:1616If any man see his brother sin a sin which is not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it. (1 John 5:16); 1 Cor. 5:2; 11:302And ye are puffed up, and have not rather mourned, that he that hath done this deed might be taken away from among you. (1 Corinthians 5:2)
30For this cause many are weak and sickly among you, and many sleep. (1 Corinthians 11:30)
; Ex. 30:2121So they shall wash their hands and their feet, that they die not: and it shall be a statute for ever to them, even to him and to his seed throughout their generations. (Exodus 30:21); Eccl. 7:1717Be not over much wicked, neither be thou foolish: why shouldest thou die before thy time? (Ecclesiastes 7:17)). This doesn’t mean that a believer who dies under the hand of God’s governmental judgment loses his soul’s salvation, for God's governmental dealings with His people pertain only to their time on earth; it does not touch their eternal standing and destiny.
The Apostle Peter is an example of a believer having a second conversion. The Lord said to him, "Simon, Simon, behold, Satan hath desired to have you, that he may sift you as wheat: but I have prayed for thee, that thy faith fail not: and when thou art converted, strengthen thy brethren" (Luke 22:31-3231And the Lord said, Simon, Simon, behold, Satan hath desired to have you, that he may sift you as wheat: 32But I have prayed for thee, that thy faith fail not: and when thou art converted, strengthen thy brethren. (Luke 22:31‑32)). Peter had come to know the Lord earlier in the Lord's ministry and was converted at that time. But then, some 3½ years later, Peter denied Him, and consequently, he needed to be converted again (Mark 16:77But go your way, tell his disciples and Peter that he goeth before you into Galilee: there shall ye see him, as he said unto you. (Mark 16:7); Luke 24:3434Saying, The Lord is risen indeed, and hath appeared to Simon. (Luke 24:34); John 21:15-1915So when they had dined, Jesus saith to Simon Peter, Simon, son of Jonas, lovest thou me more than these? He saith unto him, Yea, Lord; thou knowest that I love thee. He saith unto him, Feed my lambs. 16He saith to him again the second time, Simon, son of Jonas, lovest thou me? He saith unto him, Yea, Lord; thou knowest that I love thee. He saith unto him, Feed my sheep. 17He saith unto him the third time, Simon, son of Jonas, lovest thou me? Peter was grieved because he said unto him the third time, Lovest thou me? And he said unto him, Lord, thou knowest all things; thou knowest that I love thee. Jesus saith unto him, Feed my sheep. 18Verily, verily, I say unto thee, When thou wast young, thou girdedst thyself, and walkedst whither thou wouldest: but when thou shalt be old, thou shalt stretch forth thy hands, and another shall gird thee, and carry thee whither thou wouldest not. 19This spake he, signifying by what death he should glorify God. And when he had spoken this, he saith unto him, Follow me. (John 21:15‑19)). Note: the Lord did not pray that Peter's soul’s salvation and eternal security wouldn't “fail”—because it can’t fail—but that his faith would not fail when his heart turned away from the Lord.
James 5:1919Brethren, if any of you do err from the truth, and one convert him; (James 5:19) and Luke 22:3232But I have prayed for thee, that thy faith fail not: and when thou art converted, strengthen thy brethren. (Luke 22:32) in the J. N. Darby translation renders “converted” (the KJV) as “restored” in order to help distinguish a person’s initial conversion from a subsequent conversion that he might have. But W. Kelly states that rendering those verses as “restored” is really a paraphrase because the literal meaning of the word is converted, which is to have the heart turned toward God (Lectures Introductory to the Study of the Minor Prophets, p. 378).