Funny that you mention atheism relative to my post. This professor is also an avowed atheist. Now it all makes sense.
8-)
Nominalism, Realism and Conceptualism.
This essay directly addresses the error of Nominalism, the great error of modern philosophy. It's brief, considering the subject matter, a bit technical, but worth spending some time with.
You'll see from this article that the decline of the West began with William of Occam's proto-nominalism of the 14th century.