There are about 2,500 gods in the world.
"I am wondering why all atheists hate God, knowing that they do not believe in him!!!!"
Since I don't know which god you're referring to, I'll pick the one I think you believe in. I assume you believe in Lord Ganesha. For those who don't know about the divine qualities of this god, Ganesha is widely revered as the Remover of Obstacles and more generally as Lord of Beginnings and Lord of Obstacles (from Wikipedia).
I personally don't believe in Ganesha, but that most certainly does not mean that I hate Lord Ganesha. To moslems and xtians, Lord Ganesha would be viewed as a false god. But to those who believe in Lord Ganesha know full well that this is a real and powerful god because when they, their relatives and friends prayed to this god for help, and if the subjects had led good lives, Lord Ganesha rewarded them by removing obstacles that hindered their lives.
Along with Lord Ganesha are the priests who explain the powers of this god and collect money to be given to Lord Ganesha.
If you don't believe in Lord Ganesha, then you are an atheist with respect to Lord Ganesha. The followers of Ganesha view the god you believe in as a false god since Lord Ganesha is the only True god.
If Hindus here in Uganda tried to force a belief in Lord Ganesha on me, I would resent and resist those people. I don't worship anyone's god and I want to be left alone by those who demand that I worship their god and give money to the religious institutions that promote the belief in Lord Ganesha.
Since you don't believe in Lord Ganesha, do you therefore hate Lord Ganesha?