Maréchal was an admirer of Jean-Jacques Rousseau, Voltaire, Claude Adrien Helvétius, and Denis Diderot, and associated with deist and atheist authors.
His critique of both religion and political absolutism (Livre échappé du déluge - "Book Salvaged from the Flood", a parody of the Bible) and his atheism caused him to lose his position at the college; Maréchal was forced to live off his literary output.
In 1788, he was sentenced to four months in prison for publishing the Almanach des Honnêtes Gens ("Honest Man's Almanac").
He did not become involved in the conflict opposing Girondists and Jacobins, and became instead worried about the outcome of revolutionary events, especially after the Thermidorian Reaction and the establishment of the French Directory.
His later works include an 1801 Projet de loi portant défense d'apprendre à lire aux femmes ("Bill Forbidding the Teaching of Reading to Women"), which relates to the subject matter of women's studies and egalitarianism, as well as a Dictionnaire des Athées anciens et modernes ("Dictionary of Ancient and Modern Atheists").