Reluctantly turning the other cheek

Since I think of myself as a target reader of Ideas : A History of Thought and Invention, from Fire to Freud, I'm mystified by the author's comments in the NY Times yesterday (What's the Big Idea?):

On the other hand, not all big ideas are good ideas.
In fact, most big ideas are probably terrible ideas. What do you think
is the single worst idea in history?

Without question,
ethical monotheism. The idea of one true god. The idea that our life
and ethical conduct on earth determines how we will go in the next
world. This has been responsible for most of the wars and bigotry in
history.

Surely, the thoughtlessness of the comment is not a reflection of the
quality of the book! The ethical monotheism of the Chrisitian kind
urges me to give the man another chance.