Excerpt from page 86 of The mystery of Freemasonry unveiled:

In "THE CAUSE OF THE WORLD UNREST", I read a letter attributed by Le Diable AUXIX Siecle to Albert Pike, in which the author exposes to Mazzini the plan of attack upon Catholicism in Italy, to make it seek its last refuge in Russia. At the end of the letter he says: "Therefore, when the autocratic Empire of Russia, will have become the citadel of Papal Christianity (Papist Adonaism), we shall unchain the Nihilist and Atheist revolutionaries, and we shall provoke a formidable cataclysm, which will show clearly to the nations, in all its horror, the effect of the absolute heresy, mother of savagery, and of the most bloody disorder. Then citizens everywhere, obliged to defend themselves against an enraged minority of revolutionaries, will exterminate those destroyers of civilization, and the multitude - disillusioned with Christianity whose deist spirit will be from that moment on without direction and anxious for an ideal - without knowing where to put their worship will receive the True Light, by means of the universal manifestation of the pure Luciferian doctrine, finally made public; a manifestation which will raise a general movement of reaction, which will follow the destruction of Atheism and of Christianity, both conquered and exterminated at the same time." (LA CAUSE, 77-78)

Another excerpt from page 118 of The mystery of Freemasonry unveiled where the same section of "The Cause" is again quoted:

Authentic or not, the letter had been published long enough before the events not to be an invention accommodated POST FACTUM. Its publication is catalogued in the British Museum of London and the plan attributed to Pike is also in part in "LE PALLADISME OF MARGIOTTA," p. 186 published in 1895.