John's third letter is meant to be an encouragement to Gaius and also a warning. A man, Diotrephes has risen to a position of authority in the church and is harming the the church. He is filled with personal ambition, inhospitable, authoritarian in his leadership and slanders the Apostle John. He stands as the antithesis of biblical leadership. There is no room in the church for this kind of leadership.
John writes again to the same congregation for which he has much love and tender affection for. He writes to warn them about specific deceivers that have gone out and are seeking to infiltrate the church. The church must be on guard against any person or doctrine claiming to go ahead, progress or advance the original message of the gospel delivered once for all to the saints. For such persons who would disseminate such a message, indeed a false gospel, we, individually and corporately, must have nothing to do with them.
John has written that the church might be assured of their salvation and confirmed in their understanding of the gospel. He now concludes that though the world is in the control of the evil one, the church- which finds its origin, being and life in Christ- is secure as it is protected by Christ.
When we have assurance of our salvation, knowing that we are His children, we can have confidence in prayer. We can rejoice that all of our requests that are according to his will shall be answered! God will even use our prayers for a wayward or backslidden brother or sister as the means of reviving them again and restoring them in faith.
As we come to the conclusion of John's epistle, John shares the purpose of his letter, that 'you may know that you have eternal life'. John desires to affirm the faith of those in the church and he wants them to have certainty, confidence that they are in Christ and have received eternal life. God has given them eternal life through his Son, Jesus Christ. If we have faith in the Son, we have received eternal life.
As long as we live on this earth, we are engaged in a spiritual battle; a battle for our faith, the allegiance of our hearts, even our very souls. Scripture speaks frequently and directly about the spiritual battle we are engaged in. And John specifically encourages and instructs the church how to overcome the world.
Assurance of salvation is a blessed gift. And God wants his children to have assurance not only of His love, but also of their eternal, righteous standing before him; lest they fear the coming Day of Judgment. We can live in peace and indeed eager expectation of the coming of the Lord and have confidence for the Day of Judgment if we examine our hearts and find evidence of the work of the Holy Spirit. If we are in Christ, when we examine our life, we should see the indwelling presence and effect of the Holy Spirit, a sincere confession that Jesus is the Son of God and a heart that is full of love for our brothers and sisters in Christ.
God has first loved us and He has dealt with our sins in and through Jesus Christ. By His grace and mercy, our sins have been taken away. His love should arouse in us a wonder at the magnitude of his generosity such that we can’t do anything else but love one another. God's love generates love in us for others. No one having seen the cross and received God’s immeasurable and unmerited love displayed there can go back to a life of selfishness.
Being loved by God is the greatest gift in the world. God loves us with a perfect love. As objects of his love, we are completely undeserving. The supreme manifestation of the love of God towards us is not our present circumstances, but rather the immovable, eternal work of Christ sacrificing his life on behalf of sinners. In doing so, Jesus secured for us not only forgiveness, but righteousness and eternal life.
We live in an age of confusion and falsehood. False teachers and prophets all claim to be from God or speak for God and seek to lead many astray. John teaches the church that we must be discerning. We should not believe every one who claims a revelation from God, but rather we should test their words and their confession. The Holy Spirit aids us in our discernment and enables us to know truth from error.