Complex sentence: Islam, Christianity, Judaism and Zoroastrianism--recognized by the Constitution of the Islamic Republic of Iran, were given admission though systematic expulsion of students and faculty became clear to Bahá'ís by 1983.
Split into simpler sentences: Islam, Christianity, Judaism and Zoroastrianism--recognized by the Constitution of the Islamic Republic of Iran, were given admission. The systematic expulsion of students and faculty had become clear to Bahá'ís by 1983.