I once heard an orthodox person denouncing those who discuss articles of faith. “Gentlemen,” he said naïvely, “a true Christian does not examine what he is ordered to believe. Dogma is like a bitter pill: if you chew it, you will never be able to swallow it.”

[J’ai entendu un dévot, parlant contre des gens qui discutent des articles de foi, dire naïvement: «Messieurs, un vrai chrétien n’examine point ce qu’on lui ordonne de croire. Tenez, il en est de cela comme d’une pillule amère, si vous la mâchez, jamais vous ne pourrez l’avaler.»]

Nicolas Chamfort (1741-1794) French writer, epigrammist (b. Nicolas-Sébastien Roch)

Products of Perfected Civilization [Produits de la Civilisation Perfectionnée], Part 2 “Characters and Anecdotes [Caractères et Anecdotes],” ¶ 1148 (1795) [tr. Hutchinson (1902)]
    (Source)

(Source (French)). Alternate translations:

I heard one day a devotee, speaking against people who discuss articles of faith, say naivement: "Gentlemen, a true Christian never examines what he is ordered to believe. It is with that as with a bitter pill; if you chew it you will never be able to swallow it."
[tr. Mathews (1878)]

I once heard a pious person say naively, in arguing with people who were discussing articles of faith, "Sirs, a true Christian does not examine what he is instructed to believe. You see, it's like a bitter pill -- if you chew it, you'll never be able to swallow it."
[tr. Dusinberre (1992), ¶1148]

A devout and naïve Christian was admonishing those who questioned the articles of faith. "A true Christian must never examine the things he's told to believe, gentlemen," he said. "It's like taking a pill: if you chew it, it's so bitter you'll never get it down."
[tr. Parmée (2003), ¶363]