Well, Hinduism is a word- we can all agree on that- but what does it signify? There are several approaches to answering this question
1) Philosophical- these breakdown into three broad categories
a) Essentialist- Hinduism has an essence of some sort. Where this essence is properly cognized then the use of the word 'Hinduism' has a canonical connotation such that some process of philosophical debate will always return categorical answers to questions like ' Under what set of circumstances does True Hinduism permit or enjoin the sodomization of one's male ancestors?'. This follows from the requirement that an Essence exist in all possible worlds including ones where deontics is a dick in a phase space composed entirely of ancestral assholes. More generally, there must be some possible world where any 'ism' X permits or enjoins some totally batshit crazy Y. Now an investigation into Hinduism, on this basis- i.e. stipulating which possible worlds match with any given normative batshit crazy Y- might well reveal that Hinduism is, in essence, ontologically dysphoric- i.e. fugitive from Essentialist definition.
b) Epistemological- What do words refer to and how can we come to have certain knowledge as to their connotation? The virtue of this approach is that it enables us to say that questions of the type- 'When must a Hindu sodomize his ancestors?'- are strictly meaningless. However, any departure from this salutary stricture involves us in all manner of absurdities, such that, for example, under an 'evidentiary decision theory' approach some future act of a dead ancestor may enjoin your having to bugger him. Indeed, the same problem arises under any consistent, finitely specified, 'justified true belief' type Epistemology. This is because so long as an action can be meaningfully enjoined and so long as there is some gap between what is subjectively known and the facts of the case (absent which Epistemology is empty) there can be no certainty that some uncontroversially normative act is not, in fact, some totally batshit crazy Y, like sodomizing a dead ancestor by reason of some future action of his.
This is because any probabilistic approach is going to face the well known backward causation problem in Evidential decision theory and the same problem arises- by reason of the impossibility of establishing an entropic arrow of Time in Lewis Stalnaker counter-factual possible worlds- for any non-empty Justified True Belief type theory.
c) Instrumentalist, in the specific sense of being Soteriological, such that the purpose of any human inquiry is the salvation of the soul. Thus the question re. when to sodomize an ancestor is worthy of consideration only to the extent that it causes a re-examination of Scripture which results in some 'apurvata' (i.e. unprecedented or novel fact or normative statement) being discovered therein which in turn has the effect of burning up a fetter of ignorance arising, it may be, in the karmic apurva (i.e. effect which has not yet come to pass). The virtue of this approach, which is also its chief defect, is that it involves us in Hermeneutics- that branch of Philosophical Inquiry which most undermines the very faculty by which it progresses- like attending a wine-tasting and forgetting to spit out the wine- such that judgement is impeached by its own mode of operation.
Here, it initially appears, we are on safe ground. Hinduism has a legal definition, at least for Indian citizens, and has been instrumentalized for various Political and Social purposes by the actions of the State, the Judiciary and various other public and private bodies. However, this Legalistic approach is fatally tainted with Historicism of a particularly pernicious type such that no non-circular, unique or canonical answer can exist to the question ' What is Hinduism?' In other words, this approach begs the question and, for that reason, must be dismissed- save as a source of hilarity- from such august ratocination as characterizes this blog.
3) Scholarly- i.e. Socio-Anthropological, or some other such portmanteau term for Wonkish wanking.
It might be argued that 'Public Discourse'- even such puerile and cartoonish discourse as is practised by preening Indologists & Indian origin savants prancing farther forth into Senility or Schizophrenia - nevertheless reflects some shifting and fuzzy set corresponding to a sort of Communis Opinio which itself may not be expressible in language. The problem here is that there is no radical disjunction between this Communis Opinio and the subject we are concerned with- viz. what is Hinduism?
In other words, absent some means of demarcating such propositions as express truths about the Communis Opinio and other propositions relating to Hinduism specifically, this approach is self-vitiating and circular in a manner as mischievous as the Legalist/Historicist.
Babaji says the true Hindu only sodomizes his ancestors if and when it makes money for Babaji and I really like Babaji coz my name is Sanjeev Sabhlok and I have a CORE IDEA which proves that Hitler DID NOT believe the same thing as Swami Vivekananda because Hitler was actually a Socialist and though Vivekananda said he was a Socialist too, still my CORE IDEA is that States are very bad. Only Capitalism is good. That is why I've been a bureaucrat all my working life. Anyway, I'm not a Hindu- I said to Babaji's audience 'First you people get rid of Caste System! Then I'll say I'm a Hindu.' Babaji is so nice. He cured my piles just by looking at my face- which I use for defecation because that is my CORE IDEA. Kindly read Arthashastra & Vivekananda- who was a Capitalist and not a follower of Hitler at all. My God, you desis are so ignorant! I have explained all this in my book- 'Nehru was very bad'.