The present study examined whether IQ relates systematically to denomination and income within the framework of the g nexus, using representative data from the National Longitudinal Study of Youth (NLSY97). Atheists score 1.95 IQ points higher than Agnostics, 3.82 points higher than Liberal persuasions, and 5.89 IQ points higher than Dogmatic persuasions. Denominations differ significantly in IQ and income. Religiosity declines between ages 12 to 17. It is suggested that IQ makes an individual likely to gravitate toward a denomination and level of achievement that best fit his or hers particular level of cognitive complexity. Ontogenetically speaking this means that contemporary denominations are rank ordered by largely hereditary variations in brain efficiency (i.e. IQ). In terms of evolution, modern Atheists are reacting rationally to cognitive and emotional challenges, whereas Liberals and, in particular Dogmatics, still rely on ancient, pre-rational, supernatural and wishful thinking.