If you believe in freedom of thought and speech then you are a Zoroastrian
If you abhor lie and deceit and always seek truth and righteousness then you are a Zoroastrian
If you believe in the principle of equality of rights and duties for both men and women then you are a Zoroastrian
If your purpose in this world is to be happy by making others happy then you are a Zoroastrian.
Zarathushtra said: "ushtâ ahmâi ýahmâi ushtâ kahmâichît" which means happiness to those who make others happy” [Ushtavaiti Gatha, Verse 43.1]
If you care for the environment, including animals, plants, water and air, then you are a Zoroastrian
If you refuse blind beliefs and dogmas, and only rely on reason and wisdom then you are a Zoroastrian
But if you believe that to be a Zoroastrian, you had to be born into a Zoroastrian family then you have not understood Zarathustra’s message and mission.
"Millions of Zoroastrians in the world who do not know they are Zoroastrians!" by Khosro Khazai Pardis, published in the Mah Nameh of Sep 2003.