I would say that the argument above is
simplistic - although I cannot
refute it myself, I believe a
competent biologist would be able to. However, the closing
statements in it are indeed correct. The evolutional principle is
not as
cut and dried as many other
scientific principles (say,
gravity), because we cannot observe it in daily life. Still it receives the most
vehement and emotional treatment from both sides, and people strongly in favour of
evolutionary explanations to life do indeed tend to
pontificate in a very
fire-and-brimstone kind of way.
However, my argument would be that the fault is not with the theory - it's with the people. Fanaticism is a basic human condition, and in the absence of religion many turn to fanatical atheism, fanatical rationality or fanatical politics.
This neither disproves the existance of God nor undermines the validity of the theory evolution. It's just the way people are.