iran, like europe, has an indigenous religion. the indigenous religion in iran is called zoroastrianism, and does still exist. there are almost no practitioners of indigenous european religion today (there were still some lingering deep into the end of the european dark ages, and trickling into the renaissance, but they mostly disappeared with the european enlightenment. isaac newton, while professing christian faith publicly to avoid getting his head chopped off, was known to be a pagan and an alchemist and left quite a bit of this in his private writings. francis bacon preceded and the french revolution followed. there was something shady called free masonry that existed into the 20th century and was probably an evolution of indigenous european religon, and a modern kind of mystery religion, but it was kept secret to hide it from the christian totalitarians, partly because it was advocating for an indigenous european system of government called representative democracy, that survived in tact in britain while disappearing and being replaced with totalitarian/absolutist oriental christian monarchism almost everywhere else) but there do remain practitioners of indigenous iranian religion. one prominent/famous indigenous iranian and zoroastrian (not really, probably) of recent years was freddy mercury, the lead singer of the band queen from the 60s until his death from aids.

zoroastrianism was essentially a novel monotheist offshoot of the indo-european religion, which today only survives in the form of indian hinduism, which is the surviving religion most similar to indigenous european religion. 

there are surviving indo-european religion variants in small, isolated communities scattered across russia today that are difficult to comprehensively describe or catalog. there are convincing accounts of isolated pagan villages surviving in scotland into the 1700s and the behaviour of the american "pilgrims" seems to have broadly been more pagan than christian. as was often the case in "christian europe", which was overthrown in the renaissance and permanently killed off in the french revolution, the christianity was a facade enforced by the authorities, and they instantly went back to the old ways as soon as some difficulty like a famine arose. there are convincing accounts of child sacrifice in post-roman italy into the 10th century to ask the old gods to stop the famine or expel the barbarians, by what appeared to actually be catholic priests. these are not mythology. this is the real history. some europeans lived in these awful feudal arrangements governed by states and churches, but more europeans lived pretty separate from any state or church oversight, in autonomous and democratic collectives. the church had no more power over most europeans then than it does now. this concept of history as the european church being overthrown by democracy is a convenient fiction promoted both by conservatives narrating a return to a past that never existed and by revolutionaries creating a strawman authoritarian past to tear down to rebuild a new society on top of. but there were no monotheistic variants of indigenous european religion and the idea was largely seen as absurd. the entire pagan narrative collapses on the introduction of monotheism.

the jewish historical records assign themselves as the first monotheists but they are unreliable. most of this stuff was actually written in the 6th century ad, making the old testament in truth newer than the new testament. finding older sources than reformed judaism is actually very rare and when we do find them (like the dead sea scrolls) we learn that the jewish writing we have today is very different than the old jewish writing. we don't have actual real jewish sources from the time of the captivity, let alone the time of moses. we think much of it was written during the captivity but the sources we actually have are from after the fall of rome and in the early middle ages. further, it's actually fairly obvious that these jewish sources were overwhelmingly influenced by persian religion. who let the jews return to israel? the zoroastrians, the indigenous persians, under cyrus the great.

if there were more reliable jewish/phoenecian records from the period, they were burned in a historical event called the carthaginian genocide, which sought to eliminate carthaginian civilization from the historical record and largely succeeded. if there was anything left after that, they burned it in the temple burnings. what survived clearly confuses actual jewish history with iranian and sumerian history, and is probably based on older sumerian and iranian sources. we're consequently led to believe the jews invented monotheism because the iranian stories survived in jewish writings and disappeared in iran.

but it does follow that the indigenous iranians should actually be credited with inventing monotheism, not the jews, and the remaining practitioners of indigenous iranian religion are the last practitioners of the original form of monotheism, which heavily influenced judaism, christianity and islam. 

this is important to keep in mind when you try to understand iran, today, as it has yet to succeed in overthrowing islam and returning to it's indigenous cultural roots, the way that europe overthrew christianity in the age of reason. the people of iran are not what the iranian state projects them as, and the history books will no doubt get this wrong, as all sides project false narratives to advance their respective ideologies. 

i continue to stand with the indigenous people of iran in their struggle against islamic colonialism, which means supporting groups like the kurds, who are the real iranians seeking to reclaim their land, and not colonial actors like the son of the shah.