You need to bring the Persians forward to 228AD, at least, and notice that Mithrism is the dominant religion at the time. This was when the Sassanid period began. The Parthian's preceeded them. They were not nice people.
Please bring the Arabs back in time to the 600s (7th Century).
In 651 the Arabs beat up on the Persians big time.
Islam replaced Mithrism. It also replaced Judaism in many places. To a degree it replaced Christianity.