For NT believers there’s no doubt whatever that without Jesus, His person and work, Sin isn’t dealt with. Believers don’t need to prove again and again what no believer in 2,000 years has doubted or would dream of doubting.
Precisely how Christ “deals with” Sin is still disputed though it’s clear that the evangelical stream currently prefers the penal substitution view which I think is bad doctrine that requires either universalism or limited atonement as in Augustinian Calvinism. (I’ve worked with that some in The Dragon Slayer.) Setting aside atonement theory what’s indisputable for people like us is this: Christ dealt with Sin or it wasn’t dealt with. The Incarnation, life, death, resurrection and glorification of Jesus Christ is/are the objective realities the NT says are indispensable for reconciliation and so deal with Sin that it is not an indestructible enemy of sinners—Christ conquered it so that sinners can conquer it also [John 12:41;16.33; 1 John 5:4-5]. How He “conquered” it is complex and numerous theories are offered.
This focus on God in Christ is the “objective” side of reconciliation with God. Humanity didn’t provide that—God provided that independent of the human family. [That statement needs developed to be made clear since Jesus didn’t float down out of heaven but was born of a woman who was a child of Adam and Jesus is himself listed as a child of Adam in Luke 3.] All that is true, but it’s only on side of the “reconciliation” story. 2 Corinthians 5:18 insists that “all things” are of God (referencing the things just said) but 5.20 calls (using an aorist imperative) for humans to “be reconciled” to God. “Be you reconciled to God!” It’s clear that while human response isn’t what initiates or is the ground on which humans are reconciled to God, human response is required. The Godward side of the Story is that God does not reckon human sins against them (5.19), what should have kept humans and God alienated from one another is the human record of sinful conduct that rose out of sinful hearts. The man-ward side of the Story is what is rarely dealt with in evangelical teaching/preaching. There is still the fevered fear of “legalism” or “self-salvation”—a fear inherited from Augustine, systematized in Calvinism and Lutheranism.
All talk of earning a right relationship with God is nonsense. A saving relationship with God begins in grace, is sustained by grace and ends with grace! Paul knows that no one earns anything (Titus 3.5 is enough) but the same one who wrote Titus 3.5 wrote 2 Corinthians 5.20. The entire story of reconciliation (in any situation, human or divine) must include the attitude of both parties toward the other. There cannot be “reconciliation” while one chooses and lives out hostility toward the other. To do that is to remain alienated. There is no such thing as “being at one” when in fact one chooses not to be at one. This realignment of the heart with God is the subjective side of “reconciliation/atonement”.
God’s work of reconciliation/atonement is not done when Christ has done what He has done in His earthly ministry—He has yet to overcome the sinner’s chosen alienation. That’s where gospeling enters, that’s where the Father & Son, in and through the Spirit, brings the truth that woos and leads sinners to a transformed heart (2 Corinthian 5.19-20; John 6:63; 16:13-15; Romans 2:4; Phil 1.29; Acts 16:14; 18:27 and elsewhere).
With this work—God’s continued work of reconciling—the sinner now rejects his sin, his choice of alienation, he wants to be God’s friend and servant. He renounces his past sin and renounces the sinful bent that remains a part of him due to the years of alienation and he continues (by God’s help) to “put off” the various behaviors that were part of his “old man” status (the “old man” being his relationship to and inclusion in the first Adam—see Romans 5:12–6:6). In Jesus he is not now the same person he was before God brought him to a repentant faith. Now in faith he rejects all that the “old man” (first Adam) stands for and embraces all that the “last Adam” is and stands for (see 1 Corinthians 15:21-22; 45-49 with Romans 5.14, last phrase and 7:4-6). At no point is the sinner coerced, he is not forced to believe, his free-will capacity has not been obliterated but the truth of God so works that he is persuaded and shaped that his eyes and heart are opened by the Gospel (1 Corinthians 1:21; Acts 2.37; 16:13-15; Romans 10:17; 2 Thessalonians 2:13-14). God’s goodness leads the believer to renounce Sin in all its forms (attitude, thought and deed as well as the still existing weakness that leads to sins). This is the era, the dispensation of the Spirit in and by whom the glorified and exalted Lord Jesus makes Himself present to the world having completed in His earthly ministry, experience and glorification all that needed to be done then (John 14:16-18, 23; 16:12-15; Ephesians 3:14-21 and John 16:5-11).
This shouldn’t lead to an over–stress on “doing” or “the pursuit of moral excellence” (though we were created for good works—Ephesians 2.10; 2 Corinthians 5:15; 1 Peter 2:24; Titus 3:4-8). We must take into account the truth that God cannot have fellowship with people who choose to be “darkness” (Colossians 1:13, 21; 2 Corinthians 6:14) and who remain therefore in the kingdom of darkness. At the heart of the human response to God—which is generated by God’s saving truth—is faith. Saving faith is both receiving as true what God has revealed concerning Himself in Jesus Christ and committing oneself in trusting obedience to that faith. This is what overcomes the world. Faith says of Jesus Christ, “He is right—we are wrong; He is righteous—we are unrighteous; He is the truth—we are lies……” That believing/trusting response (which is the gift of God as well as a free human response) takes us into and is the way of life in the “new world” (new creation). In and through Him we died to the “old world” and enter that new world; we die to “the old man” and are resurrected in the “new man” (Colossian 2:12; Ephesians 2:5-6).
“Reconciliation” includes the reorientation of a heart with God’s. It includes having the mind of Christ. God’s work of reconciliation is not completed until the sinner (whatever his limitations) takes God’s purpose as his own and that begins in and continues in a denial of the self and the embracing Jesus Christ as our life and identity [(Romans 6:1-6; Colossians 2:12; 3:1-5).