Although renouncing Islam is punishable by death in Iran under Sharia, frustrated Iranians convert secretly to other religions or either atheism. It drives Ayatollahs crazy because Islamic revolution in 1979 started off with nice messages by Muslim clergies and now that they have failed, people turn back on ayatollahs and specially the religion that they advocate, Islam.
Ayatollahs are very well aware of consequences of people converting out of Islam for their regime so they are trying to pass a new draft bill that impose death penalty for giving up Islam in Iranian criminal code. For sure it will slow down converts but in the long run, Ayatollahs can't change people's mind.
Youtube user Esfandeor wrote:
An extract from State Television in Iran showing a Mullah's frustration over how Iranian youths are converting out of Islam...