Dr. Kenneth Howell Asks US About Scientism

Dr. Howell is the author of God's Two Books: Copernical Cosmology and Biblical Interpretation in Early Modern Science.As a Christian he was kind enough to write a post-publication blurb of my anthology The Christian Delusion,saying, "I liked Richard Carrier’s chapter on science. I see within it hope for an advancement of knowledge. When dealing with the ancients, Carrier is superb."

Anyway Dr. Howell values my opinion and the opinions of the commenters here at DC enough to ask us all a question pertaining to an upcoming book. It's about the notion of scientism. I'll comment on it later, but for now, have at it. See if you can explain what it is and why you either embrace it or not. Provide links if you wish. Cheers.
I am attempting to understand atheism better and want to learn from the most intelligent and well-informed atheists so as to ensure that my understanding of the subject is correct. In short, I want to look at atheism as atheists do.

Many atheists, maybe most, claim that science is the only reliable knowledge that we possess. Such a position has been called scientism. Whether one accepts or rejects that term, the atheist tends to accept the proposition that all other claims to true knowledge, especially those of religion and maybe philosophy, are bogus. Only scientific method yields true knowledge. So I have a question.

For this question to make sense, I must carefully define science. Science, for the purposes of this discussion, is not simply the requirement of empirical verification. All human beings use empirical verification every day and have been doing so from time immemorial. From ancient Babylonian astronomy to Aristotle’s Parts of Animals, humanity has been doing science in the sense of empirical verification.

By science in this context I mean modern science since about the 17th century. This includes experimental science, the manipulation of variables under laboratory conditions, but it also includes theoretical science like the kind Einstein used to develop his theories of relativity.

So my question is this: if someone believes that science in this modern manifestation --- beyond the simple sense of empirical verification --- is the only valid knowledge, is this belief:

a) the conclusion of a deductive argument, be it sophisticated or relatively straightforward? If this is the answer, I will obviously ask again for the argument.

b) a working hypothesis like most of what every day science is? That is, it could be revised or discarded when found to be inadequate.

c) an (fairly) absolute assumption which could not be discarded without doing violence to human knowledge? (much like an axiom in a geometric proof).

Dr. Kenneth J. Howell