Many Atheists upon becoming free of religion proclaim that they do not have to hate any more. Despite the admonishment, there is much hatred generated by religious belief. Bigotry also is a plentiful product. Hatred is a integral part of being one of the "Faithful".
The "Faithful" hate the believers of other faiths. The "Faithful" hate those who do not believe at all. The "Faithful" hope to their almighty god that someday, those who do not believe as they do, will burn in everlasting flames, suffering agony for an eternity.
Atheists do not have to hate. This does not mean they can not hate, only that they do not have an antiquated religion commanding that they do so. When Atheists hate, it is a conscious decision to do so. There is much less hate, which is a self-destructive force, than if they were commanded to hate those who are not the same.
It is foolish to think there will ever be a world where there is no hate. As long as there is even one person on this world the possibility of hatred exists. (One person can engage in self-hatred).
An atheist is free to hate or not. A theist is subject to the dictates of their beliefs, and more often than not, hates, consciously, or subconsciously.