Biblical explanation
First John was written in part so believers could know that they have eternal life. John says: "These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life" (1 John 5:13). Assurance begins with believing God's testimony concerning His Son. John 3:16 promises eternal life to the believer. Jesus said that whoever hears His word and believes the Father "hath everlasting life" (John 5:24). The Holy Spirit also bears witness with believers that they are children of God (Romans 8:16). At the same time, Scripture gives evidence of genuine faith. First John 2:3 says, "And hereby we do know that we know him, if we keep his commandments." This does not mean that perfect obedience is the basis of assurance. Rather, a changed life provides evidence that faith is genuine. When believers fall, they are called to confess their sins and receive forgiveness (1 John 1:9).
Key takeaway
Discipleship applies the gospel to the whole life: body, mind, relationships, work, finances, and worship. Healthy choices and faithful habits do not earn salvation; they are grateful stewardship of the life God has entrusted to us and practical ways to serve others.