Megan McArdle makes some of the right points in response to this.  I would add that totalitarian regimes have been perfectly willing to regulate sexuality in particular throughout the 20th century, and it was frequently the case that revolutionary communist forces were extremely demanding in their expectations of moral and ideological purity to the point of a secular asceticism.  There is a larger problem in the argument that theocracy is somehow inherently worse or more intrusive than totalitarianism, which is that historically theocratic governments ruled states that were not especially administratively effective, nor were they powerful enough to enforce their restrictions with the kind of thoroughgoing interference of the modern totalitarian state.  The idea that you don’t have to believe in the rules and doctrines of a totalitarian system seems to show a complete lack of awareness of the practices of indoctrination and denunciation that were certainly present in communist states.  The particularly terrifying thing about, say, a Stalinist regime was that the rules and doctrines would change from year to year and adherence to the old doctrines, which had been up until the day before perfectly acceptable and mandatory, became proof of deviationism.  At least with religious orthodoxies, whatever else you might think about them, they remain generally quite stable and fixed once they are set down.  Under Stalinism, you were expected to confess a party line that changed along with shifts in policy, and the longer you had been around the more evidence of your past deviation from the current line, whatever it happened to be, there would be.   

The post did remind me of something I have read before about the “alternative history” of the universe of The Golden Compass:

The conservative Protestant churches seem to have missed the part of Pullman’s alternative history where Calvinism was absorbed into Catholicism to create the corrupt Magisterium.

This is revealing of the author’s view of Christianity and the apparent absurdity of the world he has imagined, in which two utterly, starkly opposed confessions that are about as far apart from one another as possible somehow came together in common cause to become part of the same religious authority.  I should think that any Presbyterians who heard about this alternative history would be having so much difficulty stopping their spasms of laughter that they would not have the energy to register a protest.