It's interesting to notice that Stephen does not explain why this is the case. After all the reason that we speak could be because we are 'wired' for such. Similarly the reason we can describe the structure of nature around us with mathematics is because that's the language we have chosen to use to describe it. It's also interesting to note that our 'mathematics' have often shown to be mere approximations to describe the data we have collected so far. Relativity, ocean fine structure, and recently the new astrophysics data all lead to new mathematics to describe the phenomena and explain the data.
Stephen: *Only* an Intelligent Designer could create *both* the universe with an
interior structure based on mathematics and the human brain with the
interior structure of understanding that universe.
That of course is a circular argument. Furthermore a nature which can be described by mathematics (laws) is far more likely to be due to natural than to 'intelligent' forces.
Stephen's assertions appear to be more founded in wishful thinking, clouded by his faith than on a careful scientific analysis.