Hatred in the world is caused by jealousness and envy. If people see others are doing better and they cannot react to their position that can create hatred. Hatred can also be caused by lack of help from the able parties, hence the hopeless ones hate them. If all people could love one another, there will be no hatred.
Everything Hariboo said. Anyone can be hated for any reason at all whatsoever. Jealousy and envy are only tips of the iceberg. Revenge, hysteria, fear, etc. Hatred will never go away. It's a part of us.
The Bible prophesied that due to the "critical times hard to deal with" in which we live people would be "fierce"- 2 Timothy 3:1-5. Not to be overlooked is the is the fact that "the whole world is lying in the power of the wicked one" and that because he "keeps transforming himself into an angel of light" much of what has been done in the name of God has attributed to spreading the hate.
Satan because most people now follow Satan and not God our Father who gives us peace joy happiness health and wealth Satan as a liar and the father of it ... read the Bible it will scare the hell out of you
Power, that is all. Jealousy and sacred texts have nothing to do with it (but in some cases go alongside just well [*cough cough* crusades]) just the natural desire for human power and limitless control.