Sebastian Castellio (also Sébastien Châteillon, Châtaillon, Castellión, and Castello; 1515 – 29 December 1563) was a French preacher and theologian; and one of the first Reformed Christian proponents of religious toleration, freedom of conscience and thought. Introduction Castellio was born in 1515 at Saint-Martin-du-Frêne in the village of Bresse of Dauphiné, the country bordering Switzerland, France, and Savoy. Under the Savoyard rule his family called itself Chateillon, Chatillon, or Chataillon. Having been educated at the age of twenty at the University of Lyon, Castellio was fluent in both French and Italian, and became an expert in Latin, Hebrew and Greek as well. Subsequently, he learned German as he started to write theological works in the various languages of Europe. His education, zeal and theological knowledge were so outstanding that he was considered to be one of the most learned men of his time - equal, if not superior, to John Calvin. Regarding Castellio, according to The Right to Heresy: Castellio against Calvin of Stefan Zweig, Voltaire wrote: "We can measure the virulence of this tyranny by the persecution to which Castellio was exposed at Calvin's instance—although Castellio was a far greater scholar than Calvin, whose jealousy drove him out of Geneva." Castellio later wrote that he was deeply affected and moved when he saw the burning of heretics in Lyon by the French Inquisition, and at the age of twenty-four he decided to subscribe to the teachings of the Reformation. In the spring of 1540, after witnessing the killings of the early Protestant martyrs, he left Lyon and became a missionary for Protestantism. Early career After leaving Lyon, Castellio made his way to Strasbourg where he met John Calvin. Having made a very strong impression on Calvin, Castellio enjoyed Calvin's company so much that he remained there for a whole week in the student hostel established by Calvin and his wife. Calvin, upon returning to Geneva, asked Castellio to join him in 1542 as Rector of the Collège de Genève. Castellio was also commissioned to preach in Vandoeuvres, a suburb of Geneva. Because of his unique relationship with Calvin, Castellio enjoyed great respect in the world of Protestant Christian theology. In 1542 he published his first book of Sacred Dialogues in Latin and French. In 1543, after the plague struck Geneva, Sebastian Castellio was one of the only divines in Geneva to visit the sick and console the dying. Though