Encyclical: On Liberalism and Religious Indifferentism; Mirari Vos

In the early 1800s, the Church in France, infected by its Revolution of 1789, turned to its charismatic philosopher and apologist, Abbé Felicite-Robert de Lamennais, promoter of a movement to “catholicize liberalism.” He expounded an alien philosophy based on a new theory of certitude claiming truth does not belong to individual reason, but to the universal consent of mankind. According to him, certainty of truth was not determined by evidence, but by the authority of mankind. The true religion, he concluded, is that which can put forth on its behalf the greatest number of witnesses. His opinions on liberty of press, conscience, revolt, and democratization of the Church, were receiving popularity. This caught the attention of Pope Gregory XVI, who condemned them in Mirari Vos (15 August 1832). De Lammenais refused to submit and renounced his priesthood and Catholicism. He died unrepentant and unreconciled with the Church. “From this poisoned source of indifferentism flows that false and absurd, or rather extravagant, maxim that liberty of conscience should be established and guaranteed to each man—a most contagious error,...”