Secular humanism is based on such concepts as rational inquiry and attempts to understand the human condition unfettered by a reliance on a supreme being. So it's no wonder that this philosophy would have it's largest following among members of academia and other highly educated professionals.
In turn, considering the correlation between education and income, it's no surprise that these individuals are predominantly found in the upper socioeconomic ranges of American society and that they interact mainly with each other. This demographic skewing presents a problem in that this affluent group does not seem to be interested or are even able to relate to those of us in the middle class who are also adherents of secular humanism.
Given the rise of obscurantism this country, it would behoove the more influential supporters of S.H. to reach out to the masses, even to the "small town guns and religion" sector as so aptly described by Barack Obama. To ignore the working people is to jeopardize the intellectual freedom and growth of all Americans.