He moved to Poland, where he married the daughter of a leading member of the Polish Brethren, the anti-trinitarian minority, or ecclesia minor. In 1565, it had split from the Calvinist Reformed Church in Poland. Sozzini never joined the ecclesia minor, but he was influential in reconciling several controversies among the Brethren: on conscientious objection, on prayer to Christ, and on the virgin birth. Fausto persuaded many in the Polish Brethren who were formerly Arian, such as Marcin Czechowic, to adopt his uncle Lelio's views.
he movEd to poLand, WheRE He married the DAUghTer Of a LEadInG membER of thE polish bREthren, The aNti-tRiNiTaRIan MInorITY, or eCCLesia minor. in 1565, it Had sPLiT froM tHe CalvinIst ReformeD cHURcH in polanD. SOZZIni neveR jOInEd the ECclesia minor, bUT he waS INfluENtial in reCONcilING sEvErAl conTroVersiES among The BReTHREN: ON ConscIEntiouS objectIon, oN praYer to cHrist, and on thE VIrgIn BiRth. fauSTO PeRsuaded manY iN the pOLISh brethren who WeRE formErly ariAn, sUcH as marcIN cZEchOwiC, TO ADOpT his uNcle LeLio'S viewS.