In the years after 1550 many of these isolated impulses were unified into two religious movements: the Unitarian church in Transylvania and the Minor Reformed Church in Poland. These constitute the highest achievements of organized Antitrinitarianism in the sixteenth century.
Transylvania, comprising the eastern tip of the old Kingdom of Hungary, was an independent country from 1543 to 1691. It is now a part of Romania. A land of hills and valleys, streams and woods, its name means "beyond the forest region" (of Hungary). Peopled by descendants of Magyar and Szekler settlers and a variety of other groups, the country was an ancient "melting pot," with cautious harmony and some intermarriage the prevailing order.
Nominally Catholic until the sixteenth century, Transylvania was converted to Protestantism between 1520, when the first Lutheran books and missionaries arrived, and 1566 when the government disestablished the Catholic Church. In 1561 John Sigismund (1540 - 1571) became King of Transylvania, the first and only Unitarian king in history. John was frail and artistic, an accomplished linguist and a superior monarch. Above all, he was deeply interested in religion, and sought to pacify the conflicts between Roman Catholics, Creek Orthodox, Lutherans, Calvinists, and Unitarians in his realm. His closest adviser was Dr. Giorgio Biandrata who had helped establish Antitrinitarianism in Poland. Out of personal conviction, therefore, and practical political considerations, he fostered a policy of open discussion and broad toleration of all viewpoints which made Transylvania the freest country in Europe in religious matters.
Transylvania's first decree of religious toleration came in 1557. It was renewed in 1563. Five years later, after the Diet had voted ii unanimously with a request that John "declare and strengthen" the prior decrees, the young King issued this famous Act of Religious Tolerance and Freedom of Conscience.5
His Majesty, our Lord, in what manner he -together with his realm [i.e., the Diet]- legislated in the matter of religion at the previous Diets, in the same manner now, in this Diet, he reaffirms that in every place the preachers shall preach and explain the Gospel each according to his understanding of it, and if the congregation like it, well, if not, no one shall compel them for their souls would not be satisfied, but they shall be permitted to keep a preacher whose teaching they approve. Therefore none of the superintendents or others shall abuse the preachers, no one shall be reviled for his religion by anyone, according to the previous statutes, and it is not permitted that anyone should threaten anyone else by imprisonment or by removal from his post for his teaching, for faith is the gift of God, this comes from hearing, which hearing is by the word of God.