Hutter, Manfred. 2018. Rivalität und Konflikte zwischen Christen und Zoroastriern. Schweizerische Zeitschrift für Religions- und Kulturgeschichte 112. 91–104.
The encounter of Christianity with Zoroastrianism in the Sasanian Empire started already in the 3rd century. But it was only since the 5th century that a sizable number of Zoroastrians, mostly from the upper classes, converted to Christianity. This led to reactions by the Zoroastrian clergy against the adherents of the agdēn, the «false» or «bad» religion, as this religion was seen as unfitting to Iranian culture. Thus, Middle Persian texts discuss the necessity to avoid contacts with members of agdēn. This term is not restricted to Christianity, but can also be applied to other religions. It is only from the early Islamic period in Iran that two Middle Persian texts, the Dēnkard and the Škand Gumānīg Wizār, discuss (and refute) Christian teachings more systematically. The reason for this theological discussion about Christianity can be seen in the minority situation which Zoroastrianism faced in the Islamic period.