Christianization in the 9th and 10th centuries introduced Catholicism. After the Bohemian Reformation, most Czechs became followers of Jan Hus, Petr Chelčický and other regional Protestant Reformers. Taborites and Utraquists were Hussite groups. During the Hussite Wars, Utraquists sided with the Catholic Church. Following the joint Utraquist—Catholic victory, Utraquism was accepted as a distinct form of Christianity to be practiced in Bohemia by the Catholic Church while all remaining Hussite groups were prohibited. After the Reformation, some Bohemians went with the teachings of Martin Luther, especially Sudeten Germans. In the wake of the Reformation, Utraquist Hussites took a renewed increasingly anti-Catholic stance, while some of the defeated Hussite factions were revived. After the Habsburgs regained control of Bohemia, the whole population was forcibly converted to Catholicism—even the Utraquist Hussites. Going forward, Czechs have become more wary and pessimistic of religion as such. A history of resistance to the Catholic Church followed. It suffered a schism with the neo-Hussite Czechoslovak Hussite Church in 1920, lost the bulk of its adherents during the Communist era and continues to lose in the modern, ongoing secularization. Protestantism never recovered after the Counter-Reformation was introduced by the Austrian Habsburgs in 1620.