Can we agree that to say someone is a "good Muslim" only if he follows the rules laid out by ISIS (or something very similar), we are making a claim about how that person "ought" to behave and that "ought" must necessarily be derived from some "is"'s about facts of the world (such as the things Muhammed is supposed to have said)
In other words, this is what you claim to be able to do?
Well they have this book ... called the Quran ... and then other books that chronicle Mohammed's life that it's adherents are meant to imitate.
It's not *me* who's defining the rules, I would make better ones that everyone could agree on: like no-fat-chicks.
Alternatively, is your notion of "a good muslim" unrelated to how a muslim ought to behave?
I don't understand, that makes little sense to me.
I think you are taking "a good ..." to mean someone being a good person which is different to "a good ..." being a loyal adherent.
Being "a good Muslim" by that definition is being a psychopathic killer. You can't be a good Muslim and a good person.
I'm all for people being lying pretend fake Muslims, we need more of those. Ideally they realize that they are actually ex-Muslims and part of the human race at that point.