However, in another very important sense this commandment is new. For the first time ever the world has seen the law kept perfectly without sin by a living man, for where sin defeated every other one of Adam’s descendants, Christ was victorious; he has given us an example of righteousness in action.
One commentator asked, Is it to our comfort that the darkness is passing away, or do we still cling to it? Are our dealings with the world made tolerable by the knowledge that it is passing away, or do we wish it could last a little longer?
How can the darkness be past when in the next verse John says that some still walk in darkness? The darkness is past not for the world, but for believers in whose hearts the true light has begun to shine through the knowledge of Christ.
Does the darkness that is past refer to the time before Christ was born? How can the Old Testament period be spoken of in this way? No, John uses the term darkness to refer to the realm where sin reigns under the tyranny of Satan. The darkness is past in the case of those who have begun to follow the Light of the world, and who have God’s Spirit abiding in them.
How can this commandment be said to be true in him and in us? A commandment is not usually true or false. What John means is that the commandment finds its fulfilment in him and is us because it is obeyed: by him perfectly, and by us imperfectly but genuinely.