Keywords: Reason; Faith; Henricus Regius; Samuel Desmarets; Pierre-Daniel Huet; Pierre-Sylvain Régis.
The paper analyzes the relationship between Descartes and Henricus Regius in its last stage, marked by Regius's revelation concerning his agreement with double truth theory he learned in Padua from Cremonini. The paper deals also with the debate that took place in the Netherlands between an anti-Cartesian theologian, Samuel Desmarets, and a follower of Descartes's philosophy: the former listed a series of statements by Descartes that seemed to be literal echoes of the double truth theory, albeit presented in principle as counterfactual statements (if somebody - Descartes said - would point out a contradiction between my theses and faith...). The conclusion focuses on Huet's Censura: unexpectedly, the Cartesian philosopher P.S. Régis in the defense of his teacher openly displayed the double truth theory.