No, I mean Zoroastrian.
With Heraclius´ gamble not paying off in 622, suppose that Khosrow has no second front in 630s - Constantinople and the whole Asia Minor mopped up, Aegean and Balkans as well, and the Roman refugees in Africa and Sicily not a serious worry.
And with no second front, the Arab attack is repelled and suppressed - the Sassanids occupy Medina and Mecca and establish firm control of Arabia.
With Khosrow dying in bed in 640, Muhamed a footnote in history and Arabs a poor and suppressed people on the southern margin of Sassanid Empire... the Christian populations now subject to the Empire in the new western parts (Asia Minor, Syria, Egypt) are not as marginal as Arabs - not numerically, not economically, not culturally and probably not politically either.
What will happen to the now western Sassanid Empire, assuming that Constantinople, Alexandria and the countries in between continue to be run from Ctesiphon for the rest of 7th century?