The Deist dilemma

I'll begin by stating my interpretation of historic Deism. It's my impression that during the Enlightenment, most Deists were closet atheists. They used Deism as a stalking horse for atheism. They did so for two tactical or strategic reasons:

i) It was politically hazardous to be a public atheist back then. Deism gave them some cover. It maintained a pious facade.

ii) In addition, it gave them an opportunity to perform jujitsu. They appealed to natural religion and the natural rights of man to undermine religious autocracy and political autocracy. They deployed this weapon against absolute monarchy and state religion. 

This religious appeal was basically a ploy. If they succeeded, they could then dispense with the religious justification. It was a temporary, opportunistic means to an end. 

However, that created dilemma. Initially, the natural rights of man were grounded in nature's God. The Creator endowing humans with "certain inalienable rights."

Once invocation of the deity served its purpose in defeating autocracy, God could be discarded. Problem is, as soon as God is kicked out, you lose the foundation for human rights. You must cast about for something else to ground human rights. 

More cynical, consistent atheists like Nietzsche and the Marquis de Sade appreciated the nihilistic consequences of godlessness. By the same token, it's my impression that monarchs like Peter the Great and Catherine the Great were closet atheists who found it useful to cultivate popular piety among the masses as a way of keeping them submissive to the crown. Religious morality for the hoi polloi. That made them docile subjects. By contrast, Peter and Catherine held themselves to a very different standard. A law unto themselves.