"I'm not one of those who feel Islam is an evil religion, but avoidance of taxes and the opportunities conversion to Islam gave those who abandoned Zoroastrianism could well be why so many gave it up."
http://www.historyofjihad.org/persia.html
How Islam changed the rules of warfare making the entire civilian population of a defeated adversary, into a victim of tyranny...(snip)
The Muslim Arabs hounds who set their eyes on Persia (and the rest of the world) wanted not just to conquer land and impose new administrators and taxes, but they wanted to impose a creed on the Persians and make them as bloodthirsty in turn, to attack, other parts of the world. Those who fell victim to the swords of the Jihadis could only save their lives by becoming Muslims, and in turn bloodthirsty themselves. Islam was a curse on humankind from the word go. At the pain of death, Islam spread like wildfire into Persia, making the Persians also into bloodthirsty wolves like the Muslim Arabs. It was the Persians who a hundred years later were to take this bloodthirsty creed to the Turks and the Turks in turn a few hundred years after that were to attack Byzantine and the Balkans. Today the Persians (Iranians) have faint memories of their pre-Islamic past. The glories of Cyrus and Darius. The student community is becoming increasingly aware of their pre-Islamic past mainly through the website on the Internet, that tell the true story of Iran. And this adds fuel to the restlessness of the young among the Iranian population. Today, they must realize that the twilight of the Mullahs is the last twilight before the dawn of the post-Islamic Iran. Iranians, need to not only overthrow the Mullah regime, but also discard Islam and return to their pre-Islamic Zoroastrian roots. Here we shall trace the struggle waged by Iran (Persia) against the Arab Hordes who forcibly imposed Islam on the defeated Persians at the pain of death and torture....read more at link....