Believing that everything can be described by numbers is one thing, but using that as a basis to believe that everything is numbers sounds pretty preposterous to me.
In a previous life I might have been an avid follower of Pythagoras, but I would have gone my separate way if they insisted I take the extreme view above.
Imagine their shock (and my glee) upon discovering that pi cannot be described using a fraction made of natural numbers.
Boy were they a long ways from irrational and transcendental numbers.