John opens with the apostolic testimony: what was from the beginning, what they have heard, seen with their eyes, looked upon, and touched with their hands concerning the Word of life. The eternal life that was with the Father has been revealed. The purpose of the declaration is fellowship with the witnesses and with the Father and the Son, and the fulfilment of joy. The message is that God is light; walking in the light brings fellowship and cleansing.
1 That which was from the beginning, that which we have heard, that which we have seen with our eyes, that which we saw, and our hands touched, concerning the Word of life 2 (and the life was revealed, and we have seen, and testify, and declare to you the life, the eternal life, which was with the Father, and was revealed to us); 3 that which we have seen and heard we declare to you, that you also may have fellowship with us. Yes, and our fellowship is with the Father and with his Son, Jesus Christ. 4 And we write these things to you, that our joy may be fulfilled.
5 This is the message which we have heard from him and announce to you, that God is light, and in him is no darkness at all. 6 If we say that we have fellowship with him and walk in the darkness, we lie and don’t tell the truth. 7 But if we walk in the light as he is in the light, we have fellowship with one another, and the blood of Jesus Christ his Son cleanses us from all sin. 8 If we say that we have no sin, we deceive ourselves, and the truth is not in us. 9 If we confess our sins, he is faithful and righteous to forgive us the sins and to cleanse us from all unrighteousness. 10 If we say that we haven’t sinned, we make him a liar, and his word is not in us.
Source: ebible.org
John begins with the concrete reality of the incarnation. The eternal life that was with the Father has been revealed. The witnesses have heard, seen, looked upon, and touched. They declare what they have experienced so that the readers may have fellowship with them — and that fellowship is with the Father and with his Son. The writing is for the fulfilment of joy. The foundation is historical revelation, not speculative myth.
The message heard from him is that God is light and in him is no darkness at all. Claimed fellowship while walking in darkness is a lie. Walking in the light as he is in the light brings fellowship with one another and cleansing by the blood of Jesus from all sin. Denial of sin is self-deception; confession meets the faithful and righteous God who forgives and cleanses. To claim never to have sinned is to make God a liar.
The eternal life that was with the Father has been revealed. Fellowship with the Father and the Son is present. Walking in the light brings ongoing cleansing. We live as those who have heard, seen, and received the testimony, walking in the light without claiming to be without sin, yet confident in the faithful cleansing of the blood of Jesus.
Where is the claim of fellowship still out of step with walking in the light, and how does the promise of cleansing by the blood of Jesus meet that?