Other nobles soon followed suit and the first Calvinist synod in Lesser Poland was held in 1554 in Słomniki,[5] close to Kraków.

He was generally unpopular among the Catholic hierarchy because of his Lutheran beliefs, and when the queen was away in 1542 Abraomas was forced to leave the country.

[citation needed] In 1556, John a Lasco (Jan Łaski) returned from Western Europe to help with the organisation of the Polish Reformed church.

Unfortunately, exhausted from overwork, he died in 1560, having achieved only the consolidation of the Lesser Reformed Brethren, which shortly afterwards was weakened by the split of the Unitarians (1563).

The strength of the Polish Protestants was shown when in 1573 a law was passed foreboding any persecution based on religion, an act unprecedented in Europe of that time.

[citation needed] The Calvinists opened schools in Pińczów, Leszno, Kraków, Vilnius, Kėdainiai and Słuck.

They also printed the first complete Bible in Polish, commissioned by Mikołaj "the Black" Radziwiłł in 1563 in Brest-Litovsk.and translated by Jan Łaski.

[10] Radziwiłł also worked to change state laws to bring equal rights for reformers, as well as creating several churches in his estates.

In some regions the number of Reformed parishes completely outnumbered the Roman Catholic ones, though in proportion the movement probably never exceeded 20% of the total population and 45% of nobility.

Religious riots followed, which managed to expel Protestants from the main cities of Poland (Kraków, Poznań, Lublin) with the important exception of Wilno.

This congregation had a multicultural outlook, as apart from Polish nobles it consisted of merchants of Scottish, English, Swiss, Huguenot, Dutch and German origin.

Though this union was short-lived (dissolved in 1782), the Protestants in Poland continued to grow and expand, especially in Warsaw, whose congregation soon overshadowed any other church centre.

[15] Under constant pressure from the Prussian government by the mid-19th century, the United Church abandoned Polish in its liturgy and most of the old Calvinist nobles chose to convert to Catholicism rather than to become Germans.

The Warsaw congregation led by outstanding members dominated the rump Lesser Poland Brethren and became a leader of the denomination.

The Lithuanian Brethren maintained its synodal structure and Polish outlook, and in the beginning of the 19th century erected a monumental church in Vilnius.

[citation needed] The number of Reformed were growing too: in 1803, a colony of Czech settlers founded a town and congregation of Zelów.

The predominance of the more numerous Lutherans in the new consistory of the Calvinists, as well as the unsuccessful November Uprising in 1830 led the Tsar Nicolas I of Russia to dissolve the Union in 1849.

Despite severe Russian repression after the January Uprising (1863) in which many Reformed nobles were implicated and active, the church remained Polish and slowly absorbed and Polonised new immigrant groups that settled in the country.

The church managed to avoid any nationalistic conflict between its Lithuanian peasant members and the still predominant Polish nobles.

[clarification needed] Immediately after Poland regained its independence, both the Warsaw and Lithuanian Brethren expressed joy at the occasion and a desire to unite into one church.

In 1918, the Warsaw Brethren allowed women full voting rights in church assemblies, congregations and synods.

Due to missionary activity, a few thousands of Ukrainians were converted to Calvinism from Eastern Orthodoxy and organised into a semi-independent synod within the Warsaw Brethren.

The Brethren, now left with only 4 congregations (Wilno, Izabellin, Niepokojczyce, Michajłówka) rebuilt itself by incorporating Polish Anglicans (mainly converts from Judaism) into a separate synod, as well as by mission to Ukrainians and Belarusians.

Despite repeated attempt to unite themselves, the two churches remained separate, and in the 1930s even hostile after the Wilno Consistory engaged itself into a lucrative yet dubious business of granting easy divorces.

When he started to do so in Czech, was arrested by the Gestapo after the Christmas Eve service in 1940, deported to the Dachau concentration camp where he was murdered.

Old Calvinist churches in West Poland were taken over by the Catholics who refused to give them back; the lack of pastors was acute till the end of the 1950s.