@Ikshvaku Ananda mimamsa is to praise the state of Brahman. Although it appears to be very quantitative, it is obviously symbolic. I mean we cannot actually "measure" whether Brahmananda is 100 times more than Prajapati ananda, etc. But Brahman is nothing but the definition of the universal qualities of Indra, Agni, Vishnu, Rudra, etc.

That's why Narayana Suktam says: "sa brahmA sa shivah sa harih sendrah..." "He is Brahma, Shiva, Vishnu, Indra, etc"

Also Aitareya Up says: "eSha brahmA eSha indra eSha prajApatih..." "He is Brahma, Indra, Prajapati, etc"

So this is not a stray statement, it is the main philosophy. Otherwise the old Rig Veda statement "ekam sadviprA bahudhA vadanti" would not have such currency.

@Ikshvaku I'm sorry you see Shiva as "tamasic", but he is triguNAtIta, just like any other devata.

All the devatas are symbols that represent the ultimate reality that is the innermost truth of everyone and beyond space and time.

Their different forms are only different ways in which our human mind conceives of the ultimate reality.

@Ikshvaku Gita is not a non-Vedic text. It does contain newer ideas that are a hybrid of old Vedic philosophy and other philosophies. But the subtle thing to note is it was a teaching with a context. It contains answers to questions that a confused warrior asks on a battlefield. So we have to see the Gita from its own perspective. Some of its teachings are universal, some may not be.