But he who hates his brother is in the darkness, and walks in the darkness, and doesn't know where he is going, because the darkness has blinded his eyes.

 It may well be that we do not need to choose between these two interpretations and that they are both present. This would mean something very valuable. It would mean that we have two tests by which to judge any new teaching offered to us. (i) Is it in accordance with the Christian tradition which we have been taught? (ii) Is it in accordance with the witness of the Holy Spirit speaking within? 