As if our apostle had said, "By this we shall make it evidently appear that there is the true love of God in us, if we endeavour to frame our lives according to his commandments;" and this, he assures them, was the great commandment, which they heard from the beginning, when the gospel was preached unto them, namely, that they should believe in Christ, and love one another, and constantly persevere in the practice of these duties.
Learn hence, That obedience is the natural effect and necessary product of love, so is it the best evidence, the surest mark and sign of it. This is the love of God; that is, the surest evidence that we love him, if we keep his commandments.
Learn, 2. That it is not sufficient that we profess love to God and our neighbour, but we must walk in love, and be found in the exercise, yea, in the persevering exercise, of that grace and duty: This is the commandment, That, as ye have heard from the beginning, ye should walk in it.