Mathieu Tabaraud, Histoire critique des projets formés depuis trois cents ans pour la réunion des communions chrétiennes (Paris: 1824), 412-413, as quoted in Bernard Plongeron, "Les projets de réunion des communions chrétiennes du Directoire à l'Empire," Revue d'histoire de l'Église de France 66, no. 176 (1980), 28-29 (17-49).
Tabaraud, though, remains unsatisfied with this (ultimately Louis de Bonald's) distinction between the the politics of indifférence and the unity of croyance, and goes on to distinguish the latter from the even more crucial unity of foi:
"If all of the attempts . . . to reunite the Christian communions have failed, this is because they have all been inhabited by the same confusion: all take for basic the unity of belief [(croyance)], whereas all sincere, honest, and abiding reunion necessitates the unity of faith [(foi)]. The difference is not slight. [Argument over t]he unity of confession is a political argument that brings only the cult into play [(n'est qu'un argument politique qui met en œuvre le culte)]. The uniformity of worship or the celebration of the cult-in-common requires only exterior practices and pretends to ignore the interior dispositions of the believer. Now, only the interior dispositions, into which it would not be fitting 'to initiate a dangerous inquisition', guarantee religion, that is to say unity of faith, and faith is a gift of God. But too often the attempts at reunion have been only human enterprises. . . .
"It is necessary to insist on this radical distinction that Tabaraud makes between cult and religion because it is sometimes thought that it is an invention of the theologians of the twentieth century.... Tabaraud takes finds fault with
'that predilection, become so common, for substituting for the word religion, which supposes the interior belief of dogmas divine and invariable, that of cult, which expresses only the material and exterior part of [religion] subject to so many variations all dependent on contingent circumstances'.
"For the expert on the free thought of the eighteenth century, it is already a conviction: not only does this obsession with the cult-in-common distort [(dénature)] the true reunion of Christians; it promotes 'indifference to all beliefs, [an indifference] that supposes that everything is arbitrary in religion, everything perfectly equal in the eyes of God [(la Divinité)], no matter what idea one forms of his attributes. This system, the worst of all, which has passed from religion into morals [(les mœurs)], Bacon regarded as one of the doorways to atheism'. . . . Hence the alternative that dominates the work of Tabaraud.
"Either one remains lucid on the distinction between cult and religion and the narrow but firm way of the conditions of a reunion thus emerges:
'The reunion of the Christian communions, the object of so many desires, must therefore be founded on that tolerance so dear to gentle and upright souls, [that tolerance] committed to [(qui présente des idées d')] indulgence for the erring while simultaneously proscribing rigorously all errors; [an] evangelical virtue that establishes the progress of truth on the means of persuasion while eschewing every way of constraint, above all when it is a question of reclaiming brethren who, although separated from us by their particular belief, are not less our brothren...' (p. 6).
". . . In distinction from the Protestants [by contrast], the Catholics reunit the two powers without confounding them" (30-32).
That last judgment strikes me as counterintuitive.