Sin creates division between us and God, but the gospel restores fellowship through Jesus Christ. God is light without darkness, and we cannot claim fellowship with Him while living in spiritual darkness. Walking in the light means agreeing with God's definition of sin and confessing when His light exposes darkness in our lives. Confession brings healing and restoration, allowing us to experience true fellowship with God and others. The mark of a Christian isn't sinlessness but a willingness to bring sin into the light through regular confession.