There probably is some truth to that correlation but these days there are many factors contributing to teens/adults becoming agnostics or atheists. Lots of it has to do with what they are exposed to in society in the form of anti-religion values/anti-God/anti-religion views. Also due to cultural norms which are no longer traditional, and these modern norms being at odds with religious norms/tenets and putting these younger people at odds with their religion or confusing them about what kind of lifestyle they should lead.
Iranians though believe in fiction/fantasies that all develop from their defensive mechanisms regarding their nationalist pride/history and general human defense mechanisms. If you look at Hindu's/Buddhists/Jews/Christians/Some Shia Muslims you see these similar philosophical approach between them. They are triggering all their defense mechanisms to avoid reality.
For example, many Jews today claim there is no such thing as 'Hell' or the punishment of Hell. They say those who are evil will just have their souls disappear after death and not be admitted with God. And they even say Paradise is not a physical realm. Some Christians believe in Hell but lots don't and think Jesus bought their sins and they are gonna have no issue after death and go straight to Paradise. Same thing with Shia, they make up fictional stories to defend their national pride and integrate Persian nationalist identity into Islam, and they also don't take God's judgement seriously and permit themselves to have tattoos and do mutah and putting pictures of some early Islam figures and invoking these figures instead of invoking God. They are basically unsure and not firm in their belief of God and Islam so they make sure to change what they feel they need to change just to be on safe side; ie meaning they don't know if Islam is true and need it to work to their benefit and not take chances with actually being sincere to God.
Sunni Muslims theology is the true monotheistic theology that doesn't do anything to avoid reality. Yes, God is real, yes the Prophet's are the righteous ones, yes we will be judged by God face to face and he will either admit us into Paradise or Hell that are physical in nature. Yes, God gave us a world in which there are pleasures and in which one has to make a choice, do they want this world and will they chase after the pleasures and disregard God or will they sacrifice these pleasures and seek to worship God even though they can't see him. Most people, including many Sunni's today, are very spiritually weak and leaning to the pleasures of this world.
Lots of those kind of Sunni's and Shia's however also want benefits of what religion can bring to them. For Shia its influence in Middle East and sense of community and feeling of being a unique minority and mutah and being like Christians putting pictures of religious figures everywhere. For Sunni's they like the experience in trying to outwardly appear as pious and being respected or highly regarded as a pious figure, so they go out of their way to try to establish such an image in their local community. So they are chasing after image which is a pleasure of life and disregarding God since many of them are not genuine about their practice and worship. As you can easily identify this by observing their character. I deal with such people in personal life and they are fake, two-faced people even inside the Mosque or community center. And they are arrogant as well. And not sincere about anything.
However, everywhere in the world, there are people, whether Muslims or non-Muslims, that are sincerely good people that don't enable these defense mechanisms and don't chase after an image, and they are more in tune with reality even if its more depressing to understand the world and its inhabitants(humans) are not a good people , overall. These kind of people God will not forget them and guide them to Islam and forming a real Islamic community when God deems it the time for that.
As for now we have fake, ill intentioned, and two faced people running our mosques and community centers and not willing to step down or back down at all and they bully the sincere people out the mosques and community centers out of sheer jealously as they can too recognize the Muslims that are better than them and more sincere them and are frustrated they can't have imaan and good hearted intentions like those Muslims do. So we are just going to have to deal with this reality in meantime. But tomorrow we will be whacking them on their heads and knocking the fakeness and inclination to evil out of them.
How would you go about resolving the issues mentioned?