There are many Muslims including some Muslim scholars like this who would argue that Hijab is not a mandatory feature of Islam. Feminism and anti-hijab movement in Iran comes in two varieties - atheist/anti-Muslim and Muslim but anti-hijab. We see mostly the first in the media who are relatively less but more visible and more noisy. But the second ones are the ones more numerous in Iran according to my Iranian friend.hanumadu wrote: The fight against hijab is definitely against a tenet of Islam though it might be against Islam itself. There have been instances of burning quran in those rallies.
Also in theory we would expect people who are leaving Islam in Iran would turn to either zoroastrianism or even its close relative Vedic Hinduism. But in reality they are either becoming atheist or even more interestingly becoming Christians. According to this report, Iran has world’s fastest-growing church.