I'm not particularly satisfied with the answers that Sam Harris put forth his 10 Myths — And 10 Truths — About Atheism. Maybe he fired off this piece in haste. Maybe he doesn't have enough space to fully develop what he has in mind. I don't know.
Be that as it may, I'd like to add my two cents to his reply to the 5th myth, that atheism has no connection to science.
At first blush, there is no apparent nexus between the two. Science is the process of objectively understanding the workings of the universe. Atheism, on the other hand, is merely the lack of belief in deities (just as--to take liberty in creating some temporary neologisms--"a-fairyism" is the lack of belief in fairies, "a-Nessieism" the lack of belief in the Loch Ness monster, "a-Odinism" the lack of belief in the god Odin, and so on. Needless to say, a large number of people in the world are a-fairyists, a-Nessieists, and a-Odinists).
However, if we look at the foundations of science, the tenets which explicitly or implicitly undergird the work of scientists, then we see that one of the principles which has been at work is that of methodological naturalism (MN). In part, MN entails the assumption that empirical phenomenon Y can be explained in naturalistic terms. When scientists propound hypotheses, write papers for publications to journals, they do not tell their colleagues that Y was caused supernaturally. That just isn't science.
While scientists may have personal religious beliefs (there are scientists who are also Jews, Buddhists, Hindus, ... ) science itself does not presuppose the existence of deities and the supernatural. The scientific enterprise is predicated upon an implicit atheism. It's naturalistic. Otherwise, every time researchers bump up against a complex, seemingly inscrutable problem, they can simply throw their hands up and exclaim, "Deity Z did it." And if it isn't obvious, such an explanation is no explanation at all since anything can be attributed to such (all-) powerful entities, just as we can take it as axiomatic that a superadvanced extraterrestrial exists and then attribute everything we don't understand to it: "An alien unimaginably more intelligent and more powerful than humans caused Y." As such, "God(dess) did it" is merely a substitute for "I don't know the nature of Y," i.e., merely a placeholder/euphemism for ignorance. As biologist Jerry Coyne notes, "If the history of science shows us anything, it is that we get nowhere by labeling our ignorance 'God.'"