Lesson 1: Fellowship with the Father and the Son

John opens with his senses. What he declares is what 'we have heard... seen with our eyes... looked upon, and our hands have handled, of the Word of life' (1:1). Before he says anything about love or obedience, he grounds the faith in a real person who was physically present. The purpose of that testimony is fellowship, with the apostles and 'with the Father, and with his Son Jesus Christ' (1:3), and the result is full joy (1:4).

The first message is simple: 'God is light, and in him is no darkness at all' (1:5). Light in John stands for truth and moral purity. Then John answers three false claims, each introduced with 'if we say':

• 'If we say that we have fellowship with him, and walk in darkness' (1:6): claiming a relationship with God while living in sin.
• 'If we say that we have no sin' (1:8): denying a sinful nature.
• 'If we say that we have not sinned' (1:10): denying actual sins.

Each false claim is matched with a better path. Walking in the light brings fellowship and cleansing by the blood of Jesus (1:7). And 'if we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness' (1:9). God's forgiveness is called just, not merely kind, because it rests on what Christ has done.

John immediately guards against misuse. He writes 'that ye sin not' (2:1). But if anyone does sin, 'we have an advocate with the Father, Jesus Christ the righteous,' who is 'the propitiation for our sins: and not for ours only, but also for the sins of the whole world' (2:1–2). A propitiation is a sacrifice that satisfies God's just judgment against sin. The believer's security rests on the righteousness of the Advocate, not on a spotless record.

Christianity stands or falls on a historical claim: that the Word of life was seen, heard, and touched. John's opening is deliberately physical, and it lines up with the eyewitness emphasis elsewhere in the New Testament (Luke 1:1–4; 2 Peter 1:16; 1 Corinthians 15:3–8).

This matters for apologetics. Christianity doesn't ask people to believe in a private spiritual experience or a timeless idea. It points to public events that people witnessed. A good conversation with a skeptic often starts right here: what do we make of the testimony of people who said they were there, and who had little to gain from saying so?