Yes we are off-topic. Let us return to the Seleucid Empire...
It was an educational diversion for me, so I had fun at least. ^_^
Wait, the Achaemenids weren't Zoroastrians? What religion did they follow then?
There's a fair (but not airtight) case that Cyrus the Great was a Zoroastrian, though if he was, he doesn't seem to have made it the court religion or promoted it to his subjects. Or he may simply have been influenced by Zoroastrian ideas. (Considering the time and place, his proclamations are kinda strange and his tomb is really weird and they are weird in a way that's consistent with Cyrus - or Kourosh as we should pronounce it - being influenced by Zoroastrian ideas on wisdom and proper burial, but there are also other possible interpretations, so currently the best we can say is "maybe Kourosh was a Zoroastrian".)
I'm not aware of any case for other Achaemenid rulers being Zoroastrian. For the most part their religion seems to have been "I am emperor". The dynasty got pretty sordid in its latter days... And in an empire as large and diverse as the Persian empire, a good ruler needed to show respect to an astounding array of gods.
fasquardon