Beloved: The way we may be sure that we know him is to keep his commandments.
Whoever says, “I know him,” but does not keep his commandments is a liar, and the truth is not in him.
But whoever keeps his word, the love of God is truly perfected in him.
This is the way we may know that we are in union with him: whoever claims to abide in him ought to live (just) as he lived.
Beloved, I am writing no new commandment to you but an old commandment that you had from the beginning.
The old commandment is the word that you have heard.
And yet I do write a new commandment to you, which holds true in him and among you, for the darkness is passing away, and the true light is already shining.
Whoever says he is in the light, yet hates his brother, is still in the darkness.
Whoever loves his brother remains in the light, and there is nothing in him to cause a fall.
Whoever hates his brother is in darkness; he walks in darkness and does not know where he is going because the darkness has blinded his eyes.” – 1 John 2:3-11.