The most-likely author of 1 John is traditionally believed to be the apostle John, who was one of Jesus’ 12 disciples and the author of the Gospel of John. John was known as the disciple whom Jesus loved and was one of the inner circle of disciples along with Peter and James.

From an evangelical Christian perspective, the authorship of 1 John is important because it provides the credibility and authority of the letter as being inspired by God. Evangelicals believe that the Bible is the inspired and inerrant word of God, and they place a strong emphasis on the apostolic authority of the New Testament writings.

As the author of 1 John, it is believed that John wrote the letter to address the issue of false teachings and to encourage believers to remain faithful to the truth of the gospel. The letter emphasizes the importance of love, obedience, and the assurance of eternal life for those who believe in Jesus Christ.

In 1 John 3:18, the author emphasizes the importance of showing love not just in words, but in actions and truth. This teaching aligns with evangelical beliefs about the importance of living out one’s faith through love and good works, as evidence of a genuine relationship with God. Overall, the authorship of 1 John by the apostle John holds significant weight in evangelical Christianity and contributes to the authority and relevance of the letter for believers today.