"It has caused a lot of problems in this world, but it has not solved one yet," per Maya Angelou (4)
I believe the answer is:
hate
(Other definitions for hate that I've seen before include "Strongly dislike" , "Passion" , "[OPPOSITE OF] Be besotted with" , "Abhor" , "'Unimaginable as ---- in Heav'n': Milton" .)