Who are the people who shape this "common interpretation of Islam"?
It is not unlikely that there are more, perhaps many more people like you, who are just months or few years away from renouncing their Islamic faith, but who nevertheless still consider themselves Muslims and expect others to consider them Muslims.
Then there are people who just formally stay or become Muslim, for non-religious reasons (such as socio-economic pressures), even though they've lost their faith long ago or never even had it; yet they consider themselves Muslims.
And these people, too, are shaping what then goes as the "common interpretation of Islam."
Such potential and undeclared apostates surely cannot rightfully be considered authorities on Islam or representative of Islam.
So I question how valid this "common interpretation of Islam" can be.
I don't disagree with you. Even though people who identify with being Muslim may not be true to the actual faith or even understand it correctly, identifying themselves as Muslim makes them responsible for creating the common interpretation of what Islam is. I don't deny that the Qur'an never says how many times a day one has to pray or how they are to pray but people who call themselves Muslims insist that prayer must happen 5 times a day and in a manner of ritualistic prostration and recitation of scripture while facing in the direction of the Kaaba. This is part of the common interpretation of the faith that is not actually in the Qur'an. However it is part of the faith to be scrutinized and examined because there is a consensus among the majority of Muslims that this is indeed correct practice of the faith along with many other aspects of the faith.
I have a friend who while in Pakistan he called himself Muslim because it kept him safe from hostility. He abstains from pork, he accepted an arranged marriage, and he dresses modestly and participates in many culturally valid activities that are Islamically based. But now that he is living in UK he is honest about his religious beliefs and calls himself agnostic (on the verge of atheism). As far as I know he never prayed Islamically even while in Pakistan unless he was cornered by friends and could not get out of it. But he considered his life to somewhat depend on the deception. Something you have pointed out. But as I said, now he is in UK and free to be honest and live as he chooses. He does not claim to be Muslim. However he still abstains from pork out of habit, loves his wife which was an arrangement, and still goes to culturally valid social gatherings that are based in Islam out of courtesy and respect for his friends.
So questioning the validity of common interpretation, well I understand where you are coming from and in regards to how I personally judge a religion I still judge the religion by its texts, but I define a religion by its texts while the majority of people tend to define things by how they see it acts. Stupid is as stupid does, Islam is as Islam does.
So while I don't necessarily agree that Islam is as horrible as the majority of non Muslims think it is, I have to acknowledge that what they are considering to be Islam may not be what I am considering Islam to be.
Kinda like the word puss. To me that word may mean cat, or female genitalia, but to a Swede I believe it means kiss.
Believers may invest a lot in their religiousness. The fact that they invest so much can make them biased into thinking that they invested wisely, genuinely, productively, that they figured out the truth of their religion.
As if to say, "I spend so many hours praying and studying scriptures etc., surely I now know what my religion is about."
It's not uncommon to find ex-believers who claim to be experts in matters of God and religion. Yet that expertise can be illusory, a result of their overestimating their past religious efforts.
Well I am claiming no expertise. I do have more intimate experience with Islam than the majority of the non-Muslim western world but EXPERT? hardly. And I think you have a valid point considering how many Christians don't know squat about what is in the bible, at least not first hand. Religion, by it's nature is passed down more through tradition than the actual writings of what is in the text. This happens due to illiteracy,laziness, and of course those in high religious positions of power claiming to have a direct line to teh almighty and divine guidance in interpreting texts most people are too lazy to read for themselves. Add to that the very personal aspect of religion in which for the most part, religion is unique from one person to the next but they conform to certain rules in order to maintain a sense of community.
Even married couples will give in to the desires of their mate to maintain cohesion in the relationship. For instance a wife who knows nothing about sports and couldn't care less may be willing to throw a super bowl party to please her football enthusiast of a husband. In my case, my husband occasionally accompanies me to a karaoke bar and does his best to not scream as if he is dying while listening to strangers sing as I wait my turn, he even claims to like my singing. I think at least sometimes he is telling the truth lol.