The following graphs show the sex distributions among whites surveyed since the turn of the century by (a)theistic outlook:
Putting aside all the other reasons that men tend be disproportionately overrepresented in the top spots of movements, organizations, fields of study, etc they belong to, it's still hardly surprising that the shrew detects a dearth of women leading the secularist charge into the public square. Atheists comprise less than 3% of the contemporary white adult population, and, by a 3-to-1 margin, they're overwhelmingly men. Agnostics comprise 5.6% of the white adult population, uncertain believers 33.9%, and firm believers 57.7%.
Parenthetically, while a solid majority--65.6%--of white women express certainty in God's existence, white men who feel the same way are, at 48.3%, actually in the minority among their own sex.
GSS variables used: YEAR(2000-2010), SEX, RACECEN1(1), GOD(1)(2)(3-5)(6)