Polish Brethren

The Polish Brethren (Polish: Bracia Polscy) were members of the Minor Reformed Church of Poland, a Nontrinitarian Protestant church that existed in Poland from 1565 to 1658. By those on the outside, they were called "Arians" or "Socinians" (Polish: arianie, socynianie), but themselves preferred simply to be called "Brethren" or "Christians," and, after their expulsion from Poland, "Unitarians".

The Ecclesia Minor or Minor Reformed Church of Poland, better known today as the Polish Brethren, was started on January 22, 1556, when Piotr of Goniądz (Peter Gonesius), a Polish student, spoke out against the doctrine of the Trinity during the general synod of the Reformed (Calvinist) churches of Poland held in the village of Secemin.

A theological debate called by the Polish king Sigismund II Augustus himself in 1565 did not succeed in bringing both Protestant factions together again. Finally, the faction that had supported Piotr of Goniądz' arguments broke all ties with the Calvinists and organized their own synod in the town of Brzeziny on June 10, 1565.

In the 1570s a split was developing between the pacifist and Arian group, led by Marcin Czechowic and Grzegorz Paweł z Brzezin and the non-pacifist and Ebionite group led by the Belarusian Symon Budny. In 1579 the Italian exile Fausto Sozzini arrived in Poland and applied for admission to the Ecclesia Minor, which was refused because of his rather unusual personal objection to water baptism, however they saw in the Italian an able advocate and Sozzini's capable answering of Budny, followed by his marriage to the daughter of Krzysztof Morsztyn Sr. in 1586 cemented his place among the Polish Brethren. The calling of the group "Socinian" in England is more a result of the place given to Sozzini's writings in the publishing of his grandson Andrzej Wiszowaty Sr. in Amsterdam a century later than any role of active leadership in Sozzini's life — especially given that without submitting to baptism he could never formally join the church that later bore his name abroad.

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