
The arguments of the anonymous clandestina, hitherto known only to a small minority, entered mainstream public debate through the efforts of the fideist (and possibly crypto-atheist) 'philosopher of Rotterdam' Pierre Bayle (1647-1706). Bayle's claim in 1681 that a group of atheists could form a perfectly decent society forced the European republic of letters to consider in all seriousness the possibility of a completely secular morality.
After Bayle, The theme of 'virtuous atheism' continued to be developed by deists and atheists such as Denis Diderot and Baron d'Holbach.
However, the early elaborators of an autonomous atheistic naturalist ethics also faced certain difficulties which apologists for a religious morality were not slow to detect.
Firstly, the early atheists tended to endorse a reductionistic materialism and regarded all human actions as determined by their lower-level material constituent parts. This raised acute problems for the question of human free will and moral responsibility. Secondly, it was not clear what justified their nontheistic ethics. In the eyes of the apologists this seemed to suggest that the radical enlightenment project of establishing an autonomous secular morality led necessarily to nihilism.