Blaming the atrocities of the USSR and Communist China on atheism is like blaming the color yellow when a school bus runs you over.
Another point: Tell me, what Atheist organizations have raised money, medicine, food, clothes, shelter and gave to the poor or refugees in war torn parts of the world like the Catholic Church, Red Cross or Salvation Army? Next thing you will tell me is that the Red Cross is not a religious symbol.
The fact is my friend, you currently enjoy what Christianity has given whether you believe it or not. Freedom.
Next thing you will tell me is that there is no such thing as divine law in the Constitution.