1 John 2:10-11

The one who loves and unselfishly seeks the best for his [believing] brother lives in the Light, and in him there is no occasion for stumbling or offense [he does not hurt the cause of Christ or lead others to sin]. But the one who habitually hates (works against) his brother [in Christ] is in [spiritual] darkness and is walking in the darkness, and does not know where he is going because the darkness has blinded his eyes.