The passage you've shared provides a comprehensive perspective on the concept of salvation and the ongoing struggle with sin in the life of a believer. Here's a summary:
Foundational Salvation: Salvation begins with faith in God's offer of forgiveness through the death and resurrection of Jesus (Ephesians 2:8–9; John 1:12). This transformative process is often described as being "born again" (John 3:3). Through repentance and surrendering the old life, believers receive the new life purchased by Jesus' sacrifice (2 Corinthians 5:17, 21).
Ongoing Struggle with Sin: Despite becoming new creatures in Christ, believers may still grapple with the propensity to sin. The passage emphasizes that this struggle persists because, though forgiven, believers are still fallen human beings.
Break from the Power of Sin: Salvation breaks the power that sin once had over believers. Prior to salvation, individuals were slaves to sin and incapable of pleasing God (Romans 6:20–23, 8:8). However, through salvation, believers become children of God and experience a change in their nature, although the struggle with sin remains.
Transformation in Christ: Upon surrendering to Jesus, believers become God's sons and daughters, and while occasional disobedience may occur, the new nature in Christ thrives in righteousness. The analogy of a fish out of water illustrates the believer's nature designed for righteousness, even if there are moments of disobedience.
God's Discipline: The passage highlights God's discipline as an expression of His love. Similar to how good parents correct their children for their safety, God disciplines His children when they persist in heading toward sin. Discipline serves as evidence of belonging to Jesus (Hebrews 12:5–11).
Confession and Forgiveness: After salvation, God deals with believers' sin differently. Confession is encouraged, acknowledging the wrong and seeking forgiveness. God pardons and maintains justice through the atonement provided by Jesus.
Growing in Grace: Believers are encouraged to "grow in grace and in the knowledge of our Lord and Savior Jesus Christ" (2 Peter 3:18). Through this growth, besetting sins can be overcome, and holiness becomes the goal. The passage recognizes the ongoing struggle with sin but assures believers that Jesus intercedes for them as their High Priest.
In essence, the passage captures the tension between the new nature believers receive through salvation and the continued struggle with sin in a fallen world, emphasizing the role of God's grace, discipline, and the ongoing process of sanctification in the believer's journey.