2:3-11 What knowledge of Christ can that be, which sees not that he is most worthy of our entire obedience? And a disobedient life shows there is neither religion nor honesty in the professor. The love of God is perfected in him that keeps his commandments. God's grace in him attains its true mark, and produces its sovereign effect as far as may be in this world, and this is man's regeneration; though never absolutely perfect here. Yet this observing Christ's commands, has holiness and excellency which, if universal, would make the earth resemble heaven itself. The command to love one another had been in force from the beginning of the world; but it might be called a new command as given to Christians. It was new in them, as their situation was new in respect of its motives, rules, and obligations. And those who walk in hatred and enmity to believers, remain in a dark state. Christian love teaches us to value our brother's soul, and to dread every thing hurtful to his purity and peace. Where spiritual darkness dwells, in mind, the judgment, and the conscience will be darkened, and will mistake the way to heavenly life. These things demand serious self-examination; and earnest prayer, that God would show us what we are, and whither we are going.

10. Abiding in love is abiding in the light; for the Gospel light not only illumines the understanding, but warms the heart into love.

none occasion of stumbling—In contrast to, "He that hateth his brother is in darkness, and walketh in darkness, and knoweth not whither he goeth, because that darkness hath blinded his eyes." "In him who loves there is neither blindness nor occasion of stumbling [to himself]: in him who does not love, there is both blindness and occasion of stumbling. He who hates his brother, is both a stumbling-block to himself, and stumbles against himself and everything within and without; he who loves has an unimpeded path" [Bengel]. John has in mind Jesus' words, Joh 11:9, 10. Alford well says, "The light and the darkness are within ourselves; admitted into us by the eye, whose singleness fills the whole body with light."