Frederick also exploited Poland's religious dissension to keep the kingdom divided and open to Prussian control. Approximately ten percent of Poland's population were dissenters, as the 600,000 Eastern Orthodox and 250,000 Protestants were called, but during the 1760s their political importance was out of proportion to their numbers. Although dissenters were still free to practice their religion, own property, vote in royal elections, and serve in the army, Poland had increasingly been reducing their civic rights after a period of considerable religious and political freedoms. For example, Protestants were barred from public offices and the Polish Parliament (Sejm). Frederick took advantage of this situation by becoming the protector of Protestant interests in Poland in the name of religious freedom.