1. Hyacinthe Loyson was a Roman Catholic priest who had been a Sulpician and a Dominican novice before becoming a Discalced Carmelite and provincial of his order, but left the Roman Catholic Church, in 1869, after major excommunication was pronounced against him.
Hyacinthe Loyson was known especially for his eloquent sermons at Notre Dame de Paris and sought to reconcile Catholicism with modern ideas.
Hyacinthe Loyson was baptised Charles Jean Marie; named after the poet Charles Loyson, his uncle.
Hyacinthe Loyson was educated in Pau, Pyrenees-Atlantiques, by private professors where his father was rector of the university.
Hyacinthe Loyson's mother was of the noble Burnier-Fontonel family of the Chateau de Reiquier, Savoy.
One brother, Jules Theodore Hyacinthe Loyson, became a priest and professor at the College de Sorbonne in Paris, and one sister became a nun.
Hyacinthe Loyson successively taught philosophy at the seminary in Avignon, and theology at the seminary in Nantes and officiated in his ecclesiastical capacity at Saint-Sulpice.
Hyacinthe Loyson eventually resigned his post to assume the vows of a friar of the Order of the Carmelites, taking the religious name of Hyacinthe.
Hyacinthe Loyson then spent two years in the Carmelite convent in Lyon, and attracted much attention by his preaching at the Lycee in Lyons.
In June 1869, Hyacinthe Loyson delivered an address before the Ligue internationale de la paix, which was founded by Frederic Passy, in which he spoke of the Jewish religion, the Catholic religion, and the Protestant religion, as being the three great religions of civilized peoples; this expression elicited severe censures from the Catholic press.
Hyacinthe Loyson was ordered to retract, but he refused and broke with his order in an open letter of 20 September 1869, addressed to the General of the Discalced Carmelites, but evidently intended for the governing powers of the Church.
Hyacinthe Loyson was excommunicated and resumed his name as Charles Loyson.
Hyacinthe Loyson was warmly welcomed by the leading members of the various Protestant sects in the United States, and though he fraternized with them to a certain extent, he constantly declared that he had no intention of quitting the Catholic Faith.
Hyacinthe Loyson claimed that in 1872, before he was publicly married in England, he had his marriage privately blessed in Rome by Archbishop Luigi Puecher Passavalli.
Hyacinthe Loyson urged that every nation establish a national Christian Church and the different established Churches become an international confederation.
Hyacinthe Loyson was elected, by liberal Catholics, in the following October, in 1873, along with Hurtault and Chavard, to the three vacant parishes in Geneva.
Hyacinthe Loyson died in February 1912, in Paris, in the apartment of his playwright son, Paul Hyacinthe Loyson, and was buried in Pere Lachaise Cemetery.