Hume has long been known as a fierce critic of religion, but his position on religious issues within Enlightenment discourse is rather ambiguous. This ambiguity is closely related to his scepticism (or, more properly, agnosticism in this context). On the one hand, Hume's scepticism has been considered lukewarm compared with more adamant and clear-cut atheism among certain of his contemporaries. As Diderot attests, when Hume told Baron d'Holbach that ‘[he] did not believe in atheists, that he had never seen any’, he was surprised by the baron's reply that there were fifteen atheists among the eighteen guests in the baron's house at that moment; the baron added that ‘the three others haven't made up their minds’ (cited in Mossner 1980: 483). When Edward Gibbon visited Paris in 1763, he remarked that he could not ‘approve the intolerant zeal of the philosophers and Encyclopedists, the friends of Holbach and Helvétius; they laughed at the scepticism of Hume, preached the tenets of atheism with the bigotry of dogmatists, and damned all believers with ridicule and contempt’ (Gibbon 1961: 145; on the similar contrast between Hume and the French philosophes testified to by their Italian contemporary Alessandro Verri, see Mazza 2005: 216, 230). E. C. Mossner was right to point out that the French philosophes could not understand his agnosticism and they were inclined to think that Hume ‘had not entirely thrown off the shackles of bigotry’ (1980: 485). From Hume's viewpoint, however, bold atheists have ‘a double share of folly’ because they are not content to espouse the principle in their hearts, but also they are ‘guilty of multiplied indiscretion and imprudence’ in professing it to the public (DNR 1.18; 139). As we saw in Chapter 2, Hume's scepticism about the ultimate causes or qualities of human nature was completely consistent with the characteristic self-concealment of his personal belief in his posthumously published work: Dialogues concerning Natural Religion (1779). According to him, both atheism and materialism are dogmatic in that they are confident in their ability to grasp the ultimate causes of the nature of things, no matter how lukewarm his agnostic position appeared to the French philosophes.