I John 2:4-9

He who says, “I know Him,” and does not keep His commandments, is a liar, and the truth is not in him. But whoever keeps His word, truly the love of God is perfected in him. By this we know that we are in Him. He who says he abides in Him ought himself also to walk just as He walked. Brethren, I write no new commandment to you, but an old commandment which you have had from the beginning. The old commandment is the word which you heard from the beginning. Again, a new commandment I write to you, which thing is true in Him and in you, because the darkness is passing away, and the true light is already shining. He who says he is in the light, and hates his brother, is in darkness until now.