This is just another one of those "I can't imagine how it can be anything but thus, therefore it must be thus" line of arguments. But it is not a proof of impossibility, it is merely evidence of this particular man's limit of imagination/knowledge.
It seems to be a common fallacy engaged in by philosophers, and religious philosophers are no exception.
All genuine philosophers believe in God. Philosophy is a love of truth, after all.
The rest are just masturbatory sophists enamoured of their own Systems and hypotheses.
In any case, his conclusion re: unidimensionality is true. I can pull a dozen threads from latests posts to illustrate, if you like.