Here is another post to the conversation on the Gospel, salvation, and conversion. A study of Church history over the past 2000 years will reveal great variety in the language and understanding of these matters. However, I believe “crossing the line,” repentance, some sort of active response to God’s love expressed through crucifixion and resurrection of Jesus Christ, have been consistently present. The New Testament is full of this kind of language–it is the language of repentance, turning, decision, and choice.
“I tell you the truth, whoever hears my word and believes him who sent me has eternal life and will not be condemned; he has crossed over from death to life.” John 5:24
“There fore let all Israel be assured of this: God has made this Jesus, whom you crucified, both Lord and Christ.” When the people heard this, they were cut to the heart and said to Peter and the other apostles, “Brothers what shall we do?” Peter replied, “Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of sin. And you will receive the gift of the Holy Spirit.” Acts 2:36-37
“The Lord’s message rang out from you not only in Macedonia and Achaia–your faith in God has become known everywhere. Therefore we do not need to say anything about it, for they themselves report what kind of reception you gave us. They tell how you turned to God from idols to serve the living and true God, and to wait for his Son from heaven, whom he raised from the dead–Jesus, who rescues us from the coming wrath.” 1 Thessalonians 1:8-10
It is important to remember that though the conversion of people and our activity in it is present, the great celebration isn’t that we reached out to God’s rescuing hand–the celebration is that God does such an amazing thing: “For he has rescued us from the dominion of darkness and brought us into the kingdom of the Son he loves, in whom we have redemption, the forgiveness of sins.” Colossians 1:13-14
I highly recommend Gordon T. Smith’s book, Beginning Well: Christian Conversion & Authentic Transformation. I read it several years ago and continue to find it helpful.

Among other things, Smith examines historical and current expressions of the evangelical language related to conversion, the biblical models of conversion in the New Testament, and provides helpful exploration of our need to help “2nd generation” believers–that is people who grow up in a Christian context and are following Christ–to experience and talk about conversion. Below is an excerpt:
The notion of conversion in the New Testament is expressly trinitarian and christocentric. A conversion comes in response to the election, call and initiative of the Father and is enabled by the Spirit; there is no conversion without this call and enabling. But the very heart of conversion is encounter with Christ, and without this conscious encounter a conversion is not, properly speaking, Christian conversion. Thus conversion comes in response to an encounter with God–God’s holiness, truth and love–and it can generally be viewed as an act in response to the call of God, though that call my be presented and understood in a variety of ways.
The work of Christ makes conversion possible; even more, the actual focus and dynamic of conversion is that an individual comes to faith in Christ Jesus. Conversion is the act of believing in Jesus, choosing to follow Jesus and being united with Jesus as Lord and Savior. To be converted is to become Christ-ian. And the purpose of conversion is that we may ultimately be transformed into the image of Christ Jesus. Although all three members of the Trinity are actively involved in the conversion experience, the focus is on Christ. In fact, conversion is the fruit of an encounter with the risen Christ himself, as witnessed to and experienced within a Christian community. Conversion is not the result of an encounter with truth or principles or spiritual laws; rather, it comes from meeting Jesus.
…conversion is human activity. Conversion and salvation are not synonymous.
Conversion is the human response to the saving work of God through Christ. Conversion is the initial encounter with God’s saving grace–the steps or the means by which we enter into a redemptive relationship with God.
Salvation is God’s work and God’s work alone, unequivocally. God saves. There is no such thing as self-salvation. The salvation and transformation that we seek come wholly from the hands of God.
Subsequently, conversion is the means by which we appropriate and experience God’s saving grace. Therefore conversion has an obvious human element. It is those things that are done following such questions as “What then must I do in order to be saved?” and “How can I appropriate eternal life?” (p. 17, Beginning Well)
Followers of Jesus Christ are the only ones on the planet who have been entrusted with God’s special message of redemption through Christ and with the testimony of current experience with the Risen Lord Jesus Christ. Thus we are the only ones with the responsibility of sharing the message of Christ. Our good works–our illustration of the justice, kindness, holiness and love of God as people under the authority of Jesus Christ–serve like the miracles of Jesus as a sign meant to draw attention to this unique message: God loves you and has done all He can to establish a relationship with you through Jesus Christ; Jesus Christ offers you unmerited forgiveness of sin, unmerited communion with God forever, unmerited transfer from the judgement of hell, and unmerited grace for freedom from the bondage of “sexual immorality, impurity and debauchery, idolatry and witchcraft; hatred, discord, jealously, fits of rage, selfish ambition, dissensions, factions and envy; drunkenness, orgies and the like” (Galatians 5:19-21) and unmerited grace for displaying in greater and greater measure love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control (Galatians 5:22-23).
I am constantly challenged by the Holy Spirit to make this Gospel known and to not be ashamed of Jesus in any way. God has put power in this message because it engages people with the Risen Lord Jesus and stimulates faith. “Faith comes from hearing the message, and the message is heard through the word of Christ.” (Romans 10:17) Every follower of Christ is commissioned to make this Gospel of Jesus known, to share the testimony of encounter with Jesus Christ, and to invite others to respond positively to grace of God offered through Jesus Christ.
