question that turned up on the youtube channel [that i’ve taken .. long to respond to]; answer below:
i mean, as you know, there’s quite some complexity when it comes to this kind of theology –
for a start, it’s not always the case that a particular theonym that we are used to encountering for a particular deity, when used for another deity, actually means a direct conflation.
A good example of this is supplied to us by two different renditions in one of the Brahmanas (will have to check which one) detailing the Devata(s) for the Chitra Nakshatra. In one verse, it’s Tvasta – in another, it’s Indra.
Now, this does not mean that Indra is Tvastr.
Rather it means that ‘Indra’ here is meant in that other sense: the one around ‘Lordship’, being ‘Foremost’; (I think one of the archaic commentaries also specifies a ‘sense-engagement’ element but will, again, have to check).
However, to go further … many Hindu theonymics (indeed, theonymics all up) – are ‘functional’ ones. They describe something that a deific is doing or does.
So, for instance, Vritraghni, Vritrahan etc. … well, these terms pertain (obviously) to Slaying of Vritra. You find these utilized to hail Indra, Saraswati, Agni, I think there’s one for Trita Aptya as well.
Does this mean that all of these are the same deific? No, it means that They all do something rather coterminous, however.
As applies your question directly – it is possible to interpret some of these co-occurrences in such a manner. Indra being spoken of as having a ‘Shiva’ quality in some RV verses for instance – doesn’t make Indra Shiva, but rather shows that the term that has come to denote Rudra in later prominence … is a broader one that pertains to a quality or state / facing.
However, while we could interpret a line from the Vishnu Thousand Name Hymnal wherein Vishnu has a ‘Rudra’ hailing in that light [i.e. Vishnu ‘roaring’ or ‘wailing’ mightily] –
I would infer that it’ll be more likely to be understood in the usual Hari-Hara style of ‘Combined’ sense.
Deifics can have ‘shared’ forms upon occasion, it presumably cuts down on the paperwork and/or angry worshipper emnity.
If you’re running the ‘All Gods Are Really Just Facings Of My One God’ approach – which is quite prominent in rather direct form in the Vaishnava sphere (and, to be fair, is definitely not exclusive thereto) … then it makes additional sense.
That is – they can say ‘Vishnu is Rudra’ and in terms of that style of theology … yes, that’s what they mean.
Although having said that – various of the other elements that would be kinda similar, such as Krishna’s famous “Of the x, I am y” set of phrasings extolling His Own greatness … whilst these can be read in such terms – can also be read as straight-up metaphor.
Of [set of x], I am [apex of set x], repeated to emphasize a general apex-ness all around.
And, more importantly … it doesn’t actually provide a very useful framework (in general terms) for either Vedic or comparative Indo-European theology to basically say “well, all Gods are actually just Vishnu”.
Because it can lead to the actual points of meaningful differentiation being … eroded if not outright erased.
That is to say: it doesn’t help us to get a very clear picture of what either archaic or subsequent Hindus believed or perceived viz. Rudra or Vishnu if we aren’t acknowledging the difference ;
and that means that we aren’t, likewise, analyzing the relevant figures in light of Their rather manifestly differing underlying Indo-European theological typologies. [e.g. Krishna resonates with perhaps surprising vigour with the IE Striker/Thunderer complex ; Rudra is clearly the Sky Father].
Now, in terms on the point viz. Shaligrams – yup, very true that both Vishnu and Rudra have stone embodiments utilized in worship. Although it should be noted that there’s quite an array of diversity – the ShivLings in particular are not, contrary to occasional misperception, all black stones, for instance.
Further, it should also be noted that it is not only Vishnu and Rudra that have stone embodied forms. We would also point to Devi occurrences of this nature as well for a start.
Anyway – thanks for the question and i’m sorry it’s taken me this long to reply.