Apostasy in Zoroastrian religion is commonly defined as the rejection of religion in word or deed by a person who has been a behdin. The evidence from Middle Perian texts illuminate the strong challenges between Mazdean faith and other religions such as Christianity, Manichaeism and Judaism. They also emphasize the strong punishment called marg-arzān designated for the apostates. This article compares the Middle Persian texts on apostasy to find out about possible different views stated in Middle Persian Texts about this issue. According to these texts, there were strong challenges between Mazdean faith and other religions such as Christianity, Manichaeism and Judaism. It is also concluded that whereas capital punishment for apostasy could have been enforced during Sasanian times, it was not practiced when forcible conversion to Islam was commonplace.