1 John 2:8-9

On the other hand, I am writing a new commandment to you, which is true and realized in Christ and in you, because the darkness [of moral blindness] is clearing away and the true Light [the revelation of God in Christ] is already shining. The one who says he is in the Light [in consistent fellowship with Christ] and yet habitually hates (works against) his brother [in Christ] is in the darkness until now.