I read a letter to the editor in our local newspaper a while back expressing the marketing strategy of atheism. A summary is as follows. Atheism is the direct result of intelligent minds looking at the facts (Implication: those who believe in God are a bit dull). Atheism frees the mind from the slavery of religion (Implication: all who believe in God are slaves). Atheism delivers mankind from the cruelty of religious enthusiasm (Implication: if all people were atheists, the world would be a peaceable place).
I will only address the last point. It assumes that the great cause of evil between peoples is religion. This point is often made by atheists. But it misses a very important fact: in the twentieth century, more people were brutally killed because of godlessness than because of a belief in any god.
In one list of the top genocides of the twentieth century, Mao Ze-dong and his murder of 49 million Chinese and Joseph Stalin (killing 13 million people) top the list. These men based their philosophy on atheism. Places three and four are taken by Adolf Hitler (12 million victims) and Hideki Tojo of Japan (5 million). These men were not religious enthusiasts out of control. Hitler based his purifying of the races on the doctrine of the survival of the fittest. Next are Pol Pot of Cambodia (1.7 million) and Kim II Sung of North Korea (1.6 million), two blatant atheists. If we were just to consider the facts of the last century, we would conclude that a world made up entirely of atheists would the cruelest of all imaginable worlds.
Humans kill other humans because of their basic evil nature. Some use religion as an excuse. But without this excuse, they would still kill one another. Some form of atheism now accounts for approximately 16% of the world's population. With the killing statistics of the twentieth century as a base, we may wonder what the world will be like if that percentage becomes much higher.