Calvin was particularly outraged when Servetus sent him a copy of the Institutes of the Christian Religion heavily annotated with arguments pointing to errors in the book.

In 1553, Calvin's front man, Guillaume de Trie, sent letters trying to address the French Inquisition to Servetus.

* 1553 – Michael Servetus is arrested by John Calvin in Geneva.

During this time, the trial of Michael Servetus was extended by libertines in an attempt to harass Calvin.

Michael Servetus exchanged many letters with Calvin until Calvin decided he was a heretic.

Calvin and Servetus were first brought into contact in 1546 through a common acquaintance, Jean Frellon of Lyon.

Eventually, Calvin lost patience and refused to respond ; by this time Servetus had written around thirty letters to Calvin.

When Servetus mentioned that he would come to Geneva if Calvin agreed, Calvin wrote a letter to Farel on 13 February 1546 noting that if Servetus were to come, he would not assure him safe conduct: " for if he came, as far as my authority goes, I would not let him leave alive.

" When the inquisitor-general of France learned that Servetus was hiding in Vienne, according to Calvin under an assumed name, he contacted Cardinal François de Tournon, the secretary of the archbishop of Lyon, to take up the matter.

He said, after swearing before the holy gospel, that " he was Michel De Villeneuve Doctor in Medicine about 42 years old, native of Tudela of the kingdom of Navarre, a city under the obedience to the Emperor ". The following day he said: ".. although he was not Servetus he assumed the person of Servet for debating with Calvin ".

The difficulty in using Servetus as a weapon against Calvin was that the heretical reputation of Servetus was widespread and most of the cities in Europe were observing and awaiting the outcome of the trial.

After the death of Servetus, Calvin was acclaimed a defender of Christianity, but his ultimate triumph over the libertines was still two years away.

Following the execution of Servetus, a close associate of Calvin, Sebastian Castellio, broke with him on the issue of the treatment of heretics.

Servetus was eventually arrested, judged, and burned at the stake in Geneva in 1553 when John Calvin was leading the Reformation there.

Thanks to a common acquaintance, the printer Jean Frellon, Servetus and Calvin began to correspond.

To Calvin, who had written his summary of Christian doctrine Institutio Christianae Religionis ( Institutes of the Christian Religion ), Servetus ' latest book was an attack on his personally held theories regarding Christian belief, theories that he put forth as " established Christian doctrine ".

Calvin wrote to Servetus, " I neither hate you nor despise you ; nor do I wish to persecute you ; but I would be as hard as iron when I behold you insulting sound doctrine with so great audacity.

* Michael Servetus Research Study on the Manuscript of Paris with the description of the Pulmonary Circulation, and more works by Servetus.

They exchanged letters debating doctrine signing as Michael Servetus and Charles d ' Espeville, Calvin's pseudonym for these letters.

" Michel De Villeneuve " had contracts with Jean Frellon for that work, and the Servetus scholar-researcher Francisco Javier González Echeverría presented research that became an accepted communication in the International Society for the History of Medicine which concluded that Michael De Villeneuve ( Michael Servetus ) is the author of the commentaries of this edition of Frellon, in Lyon.

Independently from Ibn al-Nafis, Michael Servetus rediscovered the pulmonary circulation, but this discovery did not reach the public cause it was written down for the first time in the " Manuscript of Paris " in 1546, and later published in the theological work which he paid with his life in 1553.

After returning to Basel, Servetus published Two Books of Dialogues on the Trinity () which caused a sensation among Reformers and Catholics alike.

In 1553, Michael Servetus said that blood flows from the heart to the lungs, and that it there mixes with air to form the arterial blood which flows back to the heart.

As a defense of his actions, in February 1554 Calvin published a treatise titled Defense of the orthodox faith in the sacred Trinity ( Defensio orthodoxae fidei de sacra Trinitate ) in which he presented arguments in favor of the execution of Servetus for diverging from orthodox Christian doctrine.

Notably, George Huntston Williams, the great categorizer of the Radical Reformation, considered early forms of Unitarianism ( such as that of the Socinians, and exemplified by Michael Servetus as well as the Polish Brethren ), and other trends that disregarded the Nicene christology still accepted by most Christians, as part of the Radical Reformation.

The turning point in Calvin's fortunes occurred when Michael Servetus, a fugitive from ecclesiastical authorities, appeared in Geneva on 13 August 1553.

Sebastian Castellio ( 1515 – 1563 ) was a French Protestant theologian who in 1554 published under a pseudonym the pamphlet Whether heretics should be persecuted ( De haereticis, an sint persequendi ) criticizing John Calvin's execution of Michael Servetus: " When Servetus fought with reasons and writings, he should have been repulsed by reasons and writings.

Michael Servetus taught a chiliastic view, though he was denounced by the Reformers as a heretic and executed in Geneva under Calvin's authority.

Servetus wrote a pharmacological treatise in defense of Champier against Leonhart Fuchs In Leonardum Fucsium Apologia ( Apology against Leonard Fuchs ).

His teaching classes were suspended by the Dean of the Faculty of Medicine, Jean Tagault, and Servetus wrote his Apologetic Discourse of Michel de Villeneuve in Favour of Astrology and against a Certain Physician against him.

His controversial works refer to such subjects as the translation of the Bible into the vernacular, against Servetus, etc.

Servetus was gifted in languages and could have studied Latin, Greek and Sephardi Hebrew under the instruction of Dominican friars.

Servetus could have had access to forbidden religious books, some of them maybe Protestant, while he was studying in this city.

According to this theory, in 1554, after the immolation of Michael de Villeneuve / Servetus, the editors and printers that had worked with him would have decided to make a new De Materia Medica as a tribute to their colleague and friend.

Concerning the execution of Michael Servetus, Castellio wrote: " When Servetus fought with reasons and writings, he should have been repulsed by reasons and writings.

However, this had been revealed two years before by Michael Servetus in his fateful " Christianismi restitutio " ( 1553 ).

Some sources give an earlier date based on Servetus ' own occasional claim of having been born in 1509.

* Michael Servetus Research Website with a study on the Opera Omnia of Galen by the galenist Michael de Villanueva, and also the first description of the pulmonary circulation in his Manuscript of Paris in 1546.

* Michael Servetus Research Website with a graphical study on the Manuscript of Paris by Michael Servetus ( 1546 )

This plea was refused and on 27 October, Servetus was burnt alive — atop a pyre of his own books — at the Plateau of Champel at the edge of Geneva.

* Michael Servetus Research Study on the Manuscript of Paris by Servetus ( 1546 description of the Pulmonary Circulation )

Servetus was probably born on 29 September 1511 in Villanueva de Sijena in Aragon, Spain.

The most useful books of botany, pharmacy and medicine used by students and scholars were supplemented commentaries on Dioscorides, including the works of Fuchs, Anguillara, Mattioli, Maranta, Cesalpino, Dodoens, Fabius Columna, Gaspard and Johann Bauhin, and De Villanueva / Servetus.

* Michael Servetus Research Website with graphical study on the two Materia Medica, and the Manuscript of the Complutense by Servetus

Later non-Trinitarian teachers included: Abelard ( 1079 – 1142 ), who was accused of Sabellianism and forced into refuge in a monastery in France ; Michael Servetus ( 1511 – 1553 ), an eminent physician from Spain, sometimes cited as a motivating force of Unitarianism, who wrote, " There is no other person of God but Christ ... the entire Godhead of the Father is in him ", and was burned at the stake for heresy on October 27, 1553 ; Emanuel Swedenborg ( 1688 – 1772 ); and Presbyterian minister John Miller, author of Is God a Trinity?

He left one of the few contemporary notices of the young Michael Servetus as well as notes on Tyndale's abortive attempt to print his New Testament at Cologne in 1525.