Brethren, I write no new commandment unto you, but an old commandment which ye had from the beginning. The old commandment is the word which ye have heard from the beginning. (8) Again, a new commandment I write unto you, which thing is true in him and in you: because the darkness is past, and the true light now shineth. (9) He that saith he is in the light, and hateth his brother, is in darkness even until now. (10) He that loveth his brother abideth in the light, and there is none occasion of stumbling in him. (11) But 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.
The new commandment and the old commandment the Apostle here speaks of are well explained on Gospel principles. And the evidences of obedience he sums up in the fruits of obedience, as manifested in brotherly love. Not what the world seems so fond to inculcate, universal love, but the special love of brethren; and this on Christ's account. Loving them as brethren, and as members of Christ's body.