Really? News to me - my father’s family is Jewish, my mother’s Catholic, and I’ve been pretty sure my whole life I’m neither.
I’m fine if someone of Jewish descendant wants to identify as Jewish, or practice that religion, but the insistence that someone is of particular religion merely because their parents are is a mark of ignorance in my view, and possibly bigotry.
To each their own. My wife is a third-generation atheist, yet she identifies as Jewish. In fact, she bristles if you suggest to her that religion is an important component of Judaism. To her, it’s a matter of history, culture, pride, community and shared fate. She doesn’t keep kosher, but she observes the holidays - at least the ones she likes - not because God wants her to, but because her ancestors have been observing them for thousands of years. Plus the food is good.
If you don’t want to think of yourself as Jewish, that’s your right, but we’ll still be there if you need us.
Again, I didn’t put this in GQ because I’m not looking to argue that a factual answer exists.
Basically, I’m wondering…
…if someone who’s family’s previous generations were practicing Muslims would him/herself identify as Muslim regardless of religious belief as “a matter of history, culture, pride, community and shared fate,” to borrow Alessan’s words.
For example, I’ve seen comedians Aasif Mandvi and Hasan Minhaj say “I’m a Muslim” and I’ve found myself wondering if that is a statement of religious belief or a statement of cultural identity. Neither of those comedians, through their public persona, seem like they’d be strictly religious in a traditional dogmatic sense.
I don’t doubt that, outside a religiously governed society, Islam could have the equivalent of “Cafeteria Catholics” picking and choosing the parts of the religion that they like and filling in the gaps with their own ideas. So, it’s possible that those two comedians do consider themselves religious, that religion is what they are declaring when they say “I’m a Muslim” but I also wonder if when they say “I’m a Muslim” they’re not talking about religion at all.
Now, before anyone comes in with a “You’d have to ask them” response, I’m not asking anyone to answer on behalf of either of those two men. I’m just wondering if self-identifying as Muslim could be only a cultural identity with no connection to religion.
Why? What would lead you to believe they don’t pray 5 times a day, don’t practice charity, et cetera? Most Muslims aren’t Wahabis, same as most Christians aren’t Jack Chick.
Nothing leads me to believe anything. I said I wonder.
In the same post you quoted, I illustrated the spectrum of religious adherence that I expect is possible even making the comparison to Cafeteria Catholics who pick and choose the parts of the religion that speak truth to them while dismissing the parts that don’t.
An important difference, as I understand it, between Judaism and Islam is that Judaism is not a religion that tries to convert people - an important aspect of being Jewish is your biological heritage. You can convert to Judaism if you like, but its not going to be the same as if you had Jewish ancestors.
Islam is much more like Christianity, in that it is evangelical: converts are sought after and welcomed. Anybody is potentially a good Muslim, as long as they choose the faith and do what is required of them to adopt it.
This doesn’t directly answer the OP’s question but I think it does shed some light on the situation.
Do you also wonder what degree of “dogmatic adherence” applies to stand-up comedians of other religions?
When I hear a Jewish comedian say “I’m Jewish” I never assume that means that they’re religious. I always recognize that it might mean that they are religious.
When I hear a comic say “I’m Catholic” I just assume they’re setting a cultural backdrop for how they were raised. They might be religious but I’m never inclined to assume so.
Same as if a comic said “I’m a Lutheran”.
I know lots of comics and only very rarely have I come across one who is religious in any kind of traditional dogmatic sense and straight up atheists probably top the 50% mark.
If a comic said “I’m Christian” I’d probably assume that they were religious because, in my experience, people who announce themselves simply as Christian without noting a denomination tend to be extra religious.
You can’t help being marked by your upbringing, even in whatever adult belief system you adopt. There can be noticeable differences in attitudes and behaviours between Catholic, Anglican and Calvinist atheists, at least to the extent that they are still reacting against different aspects of their upbringing, and I don’t doubt the same would be true of Jewish and Muslim atheists.
The answer to the question imagined by the OP would depend on the circumstances. If you’re asked for the purposes of monitoring for discriminatory practice or census statistics (which is the most likely circumstance I could think of), then why not give the answer that identifies your heritage, even if you don’t fully subscribe to all the beliefs?
If you’re asked a Yes/No question by an immigration official or someone else whose purpose isn’t entirely obvious and might well mask some sort of risk of discriminatory practice, the obvious and not dishonest answer would be “No” or “I’m not religious”, and nothing more. Bigots, by definition, aren’t entirely open to reason, so a fully articulated answer to the OP’s suggested question (e.g., “I was brought up [in religion X] and am therefore of that cultural heritage, but I don’t subscribe to its supernatural beliefs or all its cultural practices and behaviours, let alone those malevolent intentions you might be ascribing to it”) might well go over the questioner’s head, or indeed, just evoke the reaction “Let’s just see if you’re such a smartarse after a couple of hours locked up”.
Thank you. 
Hijack?
From the OP:
/“hijack”
Well, it’s the OP’s issue so I should stay out of but the subject is about Islam, the bottom line is about Islam. Compare/contrast to other religions seems fair game but not “I’m Jewish” “No you’re not!” “Yes he is!” “No he’s not!”
This is a very modern thread 
The difference in race and ethnicity have been pretty well set in sociology for a long time. Popular usage is a whole 'nuther ball of wax.
IMO, personal beliefs are different than cultural ties. While kayaker doesn’t share the belief system of either the Jews or Christians, there are cultural ties to both. Same with me and the Catholics or my dad and the Lutherans (we’re both long time agnostics but were brought up in a a church).
Religion does tend to be a culture in and of itself. It’s part of tribal identity. If a parent practices ritual of said religion, as a child, you become aware of it and identify it as part of the family structure and therefore, part of you. You really don’t have to believe in FSM to identify the noodly appendages with being something that you grew up with. 
Mandvi and Minhaj are both very obviously NOT White or Black, being of South Indian origin. They stick out as outsiders; thats the very first thing that people think of them regardless of their own religious beliefs. Also as both of them are of South-Asian origin, a region where yes religion is also an ethnic identity so that probably plays into as well.
Compare with Dr Oz and Hakeem Olajuwon, who don’t check the “muslim” box at forst glance.
Here is a discussion of the subject:
It appears that it is up in the air, with different interpretations being applied to different situations. A widespread custom is to consider that a person over the age of 15, of sound mind, who fails to attend Friday prayers regularly, is considered to not be a Muslim any more.
However, some countries have their own definitions for demographic purposes. Mauritania, an Islamic Republic, regards every citizen of the nation to be a Muslim, and an immigrant cannot be granted citizenship without a formal declaration of Islamic faith. But this does not mean that a denier of Islam would lose his otherwise rightful citizenship.
When I was issued my Jordanian residence card, there were simply two check boxes: Muslim and Christian. “Other” was not an option. Any person is simply deemed to be one or the other. They didn’t ask me which I was. I had friends who were non-practicing Muslims, basically “free-thinkers”, who still called themselves Muslims. Just as I have American friends who call themselves Jews, even though they are essentially atheists.
For the most part, Islam embraces anyone whose ancestry is a nominally Muslim family and has a Muslim name, even those who are lapsed, since it would be rare for any Arab to be questioned about his status as a Muslim. Islam is much more about charity than about punishment, and anyone who can credibly claim to be a nominal Muslim will be happily afforded the hospitality and generosity of Muslim society and culture, no questions asked.
I agree that context matters, and needs to be part of the discussion of any particular person’s experience.
When we’re talking about a “Muslim ban,” it’s fair to call that racist. No one is looking to ban Muslims born in England who have blonde hair. They’re also not keen on allowing entry of Iranians who are also Christian (yes, there are some). So, in that context, “Muslim” is a racial label that one can’t escape by the simple action of not being religious. And it seems right now to be filling - albeit ill-fittingly - a racial category in the US that doesn’t have another name - those people from the Middle East who aren’t culturally/ethnically/racially “White,” but we don’t have a non-religious race name for them yet.
If a stand up comedian is making jokes about his childhood days at madrassa or the way his father interrupted his soccer game to pray, then maybe I’d refer to that person as Muslim, even if now atheist, because his Muslim heritage is relevant to his current work.
If we’re asking specifically, “what’s your religion?” and a person says, “I don’t have one, I’m atheist,” then I wouldn’t call him a Muslim, because this context is about his personal religion.
So the very same person might be Muslim, Muslim, and Not a Muslim, depending on the conversation we’re having.
As for ex Catholics, Lutherans, et al, what I generally hear from them is, “I was raised Lutheran,” or “I’m a former Lutheran,” or “lapsed Catholic,” or even, “recovering Catholic.” Modifiers that let you know they were once of that religion, but are not anymore.
I do agree that Jewish people are different than other religions, because their ethnicity and their religion share the same name, more often than not. Yes, there are Ethiopian Jews and Black Jews - but in my experience, the modifiers are always used when referring to them.
I’ve never, ever heard a person refer to themselves as a “former Jew.” They may say, “I’m Jewish, but not religious,” or “I’m culturally Jewish,” but it seems once a Jew, always a Jew, even if an atheist.
This is the sort of thing that’s going to vary by denomination (some of the more Orthodox are less friendly to converts), but as a broad rule we do not draw that sort of distinction between born Jews and successful converts. In fact, the Torah tells us to take especially good care of them.
By some ways of thinking, converts are more inherently holy than those born Jewish. Ethnic Jews don’t have a choice - we’re born into the covenant. Converts, though, have made a conscious decision to bind themselves to it - and why should they? It’s much, much easier to be a righteous gentile than to be a righteous Jew.
There are also some who believe that those who feel a ‘pull’ towards converting feel that way because they already have Jewish souls - either in whole or in part. In that sense, these converts are only correcting a technical error.