Bradley is one of the few people who has written on the current awakening happening in Iran. It is hard to get information related to it, and harder still to explain why it is happening in Iran, rather than in, say, Jordan or Syria, countries with great religious freedom (relatively speaking). Bradley proposes that the Shia-Sufi DNA of Iranian Islam is a key factor:
“The Shia faith instills the importance of a just Imam, who is willing to die for his people, yet still present to guide, and certainly determined to return to return in victory; and the philosophy of Sufism invites everyone to move beyond rigid religion, and embark on a journey where they deny themselves to experience the light. As disillusionment with the Islamic revolution has spread, so the appeal of a religion which shares so much with Shiism and Sufism has increased—especially when shed of its Western externals. Rather than being the enemy of Christianity in Iran, the dual religious identity of Iran might prove to be its best friend.” p. 22
Bradley, Mark. 2008. Iran and Christianity: historical identity and present relevance. London: Continuum.
If you are interested in the topic and want to read his ideas, that book I just quoted from is the more rigorous and detailed one, but it's hard to find and expensive. Rather, order his earlier and more basic (but much cheaper) Iran: Open Hearts in a Closed Country.