Brothers, I write no new commandment to you, but an old commandment which you had from the beginning. The old commandment is the word which you heard from the beginning.

 2:3-6 And it is by this that we know that we have come to know him--if we keep his commandments. He who says, "I have come to know him" and who does not keep his commandments is a liar, and the truth is not in such a man. The love of God is truly perfected in any man who keeps his word. This is the way in which we know that we are in him. He who claims that he abides in him ought himself to live the same kind of life as he lived. 