I John 2:7-11 The Old Becomes New-Abiding In The Light.
Jesus was asked what is the greatest commandment and His answer went back to the law-to love God and neighbour-Dt. 6:5; Lev. 19:18 In this sense it is an old command (v. 7). However, Jesus also makes it new. John says that this command “is true in Him and in you, because the darkness is passing away, and the true light is already shining” (v. 8 Cf. 3:11, 23; Jn. 1:9; 8:12; 12:35; 13:34; 15:12). ‘alathes’ means it is true as in not concealed (Strong’s). So in Christ and his people, this command is seen in him and them in practice. This is what John means by the light shining. To say one is a believer, or living in the light, but hates a brother, is to actually be living in darkness-actions reveal the truth of one’s condition (v. 9 Cf. Jn. 12:36; I Cor. 13:2). This is what John meant by God’s love being perfected or reaching its completion in us (Cf. 2:5; 4:12).
This is also related to abiding, and the assurance that attends those who know that they abide in him. “He who loves his brother abides in the light, and there is no cause for stumbling in him” (v. 10). “We know that we have passed from death to life, because we love the brethren. He who does not love his brother abides in death” (4:12). ‘skandalon’, the word translated as “cause for stumbling,” is where we get the word scandalous, also meaning a snare or trap. Therefore, if we love our brother, then there is nothing to cause us to doubt our confession, because we have grounds for our assurance that we abide in him. Those who hate the brethren have no such assurance or confidence that they abide in the Lord. Those who hate without repentance or acknowledging such sin, are in a darkness that blinds them to the truth (v. 11 Cf. 3:15; 4:20).