His letter doesnt grasp how evolution can be both a fact as observed in nature and exploited in energy and agriculture, while simultaneously being a well-supported theory describing the interrelated nature of all of life.
His letter also fails to grasp that some fields of knowledge have limits either built in or beyond current understanding. Despite the fact that evolution as a theory about existing life is not tied to and has nothing to say about the fortuitous primordial processes that contributed to the origin of life, Oxsens letter makes up a requirement for a connection and jumps to a choice between the simplistic and the fantastic.
Similarly, while astronomy and high-energy physics bring us within a fraction of a second of the Big Bang event, our understanding remains firmly locked on this side of the moment it all began. Oxsens letter bridges our ignorance of pre-universe conditions with a choice between the simplistic and the fantastic. In reality, the choices remain more open, including the possibility that, in a preceding universe, physicists figured out what caused their Big Bang and ran the experiment to check their figures.