Why are Atheists denouncing God?

In my country, Most are Buddhists. They don't believe in God but they don't denounce God. We also welcome other religions also. We believe in living together peacefully no matter what religion or race we are. Though Buddhists don't believe in God, they believe that there is force in the Universe which holds things together and they also believe that there are other ways to attain enlightenment, salvation or self-realization also.