Love is a Pain

"Those who say that they are in the light but hate other believers are still in the dark. Those who love other believers live in the light. Nothing will destroy the faith of those who live in the light." - 1 John 2:9-10 (GWT)

Light and Darkness
John constantly uses the pictures of light and darkness as metaphorical examples of how people live on earth. Those who live in light are true followers of Jesus Christ; those who aren't true followers of Christ live in the darkness. Obviously, "light" and "darkness" here refer to the spiritual condition of a person.