Light contrasted with darkness. This is a concept that John talks about often. A true Christian is “in the light.” This refers to a right relationship with God, who is our illumination. It is the place a Christ is supposed to be. But, any man who claims such a place, and yet shows hatred for others (in this context, another brother in Christ) remains in the darkness rather than the light.
God loves the world (cf. John 3:16). Love must be characteristic of His children, especially love for those in this glorious family. If we love our brother we abide in the light, “and there is no cause for stumbling.” (10) Light illuminates, making the way easy, and directing the paths of the child of God.
However, hatred keeps one from the light. Without light we do not know where we are going. Sightless and yet walking is a dangerous proposition. Physically we can stub an toe. Spiritually we can lose our soul, a far worse possibility.
Love is the answer. Love for one another. Don’t fool yourself!