"Iranians turning away from Islam because of clerical regime!!" is one of the oldest Zionist propaganda lines out there. I remember reading it 15-18 years ago in some articles in late 2000's when Netanyahu was trying to push Bush to bomb Iran because it was few weeks away from a nuke. The reality is Iranians are diverse in their religiousity, some are devout, some are moderate, some have left religion altogether.
During both of my Umrah's in back to back years, there was no shortage of Iranian flags among all the umrah tour groups.