Supreme Court has as much authority in determining Hinduism as the sparrow outside my house. In legal contexts for the ease of matters of State such distinctions may need to be made, but not in any other respect.
I agree that the Supreme court of India has no religious authority in defining Hinduism. However, I was merely showing you when there is need to produce a definition, even the Supreme court was forced to accept Hinduism is the religion of the Vedas. The demarcation point between a Hindu and non-Hindu is their conformity to the Veda. Does this mean that Tantra is excluded? I will answer that next
And I can quote you many religious books saying that Carvaka, Ajjivika, Tantra etc. are non-Vedic heterodox traditions of Hinduism.
Carvaka and Ajivika are no doubt anti-Vedic nastka traditions, this is why theya re not considered Hindu. However, is Tantra a non-Vedic nastika tradition? It is not. I admit it very far from the orthodox Vedic tradition, but it still within the tradition, as much as Protestantism is within the tradition of Chrisrianity. Why is it still within the tradition? Here are the reasons
1) It still worships Vedic deities: Shiva, Devi, Vishnu, Krishna, Saraswati, Lakshmi etc
2) It still occurs within Vedic sects Vaishavism, Shaivism and Shaktism
3) It still refers to as its main scriptures Vedic scriptures e.g. Tantric Vaishnavism still refers to the Bhagvad Gita, the Vishnu Puranas and Suktas like Purusha Sukta in addition to the new Vaishnava Agamas; the Shaiva Tantras still refer to the Shaiva Upanishads, the Shaiva Puranas and Rudra Sukta of the Rig Veda. The Shakta tantra stiill refer to the Devi Mahatyma, the Puranas and and Suktas like the Devi Sukta,
4) It still accepts the 20 core universal beliefs I listed earlier
5) It still at large accepts the authority of the Veda
6) All of the Tantra concepts are traceable to the Vedic tradition e.g. Nadis which are articulated in greater detail in the Tantra texts such as Hatha Yoga is first mentioned in the Upanishads and Yoga Sutras. Same with asanas and pranayamas.
Using the name of the same deity does not make it the same religion. Otherwise Judaism and Christianity and Islam would have been the same religion.
This would be true, if they did accept the same deities. However, we know they don't. The deity of the Jews is Yahwah. Of the Christians it is Jesus who is also Yawah(Jews reject that) and of the Muslims it is Allah(Jews and Christians reject that) Hence, we can demarcate them as separate religions. They themselves insist that they are not worshipping the same God.
In contrast, Shiva of the Veda is the Shiva of the Shaiva Tantriks too. They refer to the same mythology in the Mahabharata and Puranas. The same mantras are invoked as in the Rig Ved, such as the Rudra Suktam, which is still chanted by Shavites all over India today. The refer to the same Shaiva Upanishads and the same descriptions. Nor is Tantra a separate system of philosophy, it is based on an amalgamation of Samkhya, Vedanta, Yoga and Bhakti. See the list of tattvas in Shaiva:
The 36 Tattvas and Their Significance
The first 25 are exactly the same tattvas of Samkhya. To it adds the 6th tattva from Yoga of Ishvara. To it adds the 'Maya' of Vedanta to to get 26. It then subdivides Ishvara tattva into 5 aspects: Shudda Vidya, Ishvara, Sadashiva, Siva and Shakti(further divided into five)
What is clear to scholars is that this is a later and continuous development of Hindu philosophical thought from its earliest proto-form in the Rig Veda, to its Upanishadic form, then its classical form and then its Puranic form. The final form is its Tantric form in the medieval ages. Hence, why we know it is exactly the same religion.
It is also officially recognised as a sect of Hinduism.
There is far far greater differences between the Agama religions and Vedic religions than between Judaism, Christianity and Islam. If you just list the number of theological points differentiating the various agama and vedic religions and compare them to the differences in Judaism, Islam and Christianity...you will see this clear as day.
Show, don't tell.
Your argument that some of the Rig Vedic Goddesses changed their names and became the later Agamic deities is just apologetic gloss done by later commentators in order to bring autonomous sakti religious traditions into the fold.
This is not my argument, this is what the scholarship shows. The earliest proto-form of the Goddesss in the Vedic tradition is found in the Rig Veda. Where it describes Aditi as the mother of the Adityas Indra, Surya, Mitra, Varuna, Bhaga, Aryaman, Ansa, Vivasan/Martanda, the chief among them being Indra. Aditi is described as "deva-mata" mother of the gods, she is described as the Goddess of Earth and space and is described as mighty and powerful. Her name "Aditi" literally means boundless which is later associated with the notion of infinite. She is described 80 times in the Rig Veda. See:
Aditi - Wikipedia
There is also a specific verse dedicated to Devi, entitled Devi Suktam:
I am the Queen, the gatherer-up of treasures, most thoughtful, first of those who merit worship.
Thus gods have established me in many places with many homes to enter and abide in.
Through me alone all eat the food that feeds them, – each man who sees, breathes, hears the word outspoken.
They know it not, yet I reside in the essence of the Universe. Hear, one and all, the truth as I declare it.
I, verily, myself announce and utter the word that gods and men alike shall welcome.
I make the man I love exceeding mighty, make him nourished, a sage, and one who knows Brahman.
I bend the bow for Rudra [Shiva], that his arrow may strike, and slay the hater of devotion.
I rouse and order battle for the people, I created Earth and Heaven and reside as their Inner Controller.
On the world's summit I bring forth sky the Father: my home is in the waters, in the ocean as Mother.
Thence I pervade all existing creatures, as their Inner Supreme Self, and manifest them with my body.
I created all worlds at my will, without any higher being, and permeate and dwell within them.
The eternal and infinite consciousness is I, it is my greatness dwelling in everything.
– Devi Sukta, Rigveda 10.125.3 – 10.125.8,[33][34][35]
Durga - Wikipedia
The goddesses mentioned in the Rig Veda include Saraswati, Usha, Pritvhi, Vak, Ratri, Aranyani and in late Vedic texts Sri/Lakshmi. We still worship many of them today.
Later, in the Upanishads the goddesses are all merged into one primordial nature or mother become Maya, Shakti and Prakriti and is associated directly with Brahman as his energy:
10. Know then Prakriti (nature) is Mâyâ (art), and the great Lord the Mâyin (maker); the whole world is filled with what are his members.
Svetashvatara Upanishad, Fourth Adhyaya
In post-Vedic texts the first mentions of Durga are found in the Mahabharata and Ramayana, including the popular story of her slaying an Asura called Durg.
In the Puranas which is responsible for most of the pantheon of Hindu Gods and goddesses, the various forms of Devi appear Durga, Kali, Lakshmi (Saraswati is already an old Rig Vedic goddess) The first explicit mention of Durga is in the Devi Mahatmya, which is appended to the Matendra Purana, and it is the principal text of the Shaktas. It it from this we get the famous mythology of Durga as "Mahishasura maradini"
Devi Mahatmyam is also known as the Durgā Saptashatī (दुर्गासप्तशती) or Caṇḍī Pāṭha (चण्डीपाठः).[6] The text contains 700 verses arranged into 13 chapters.[7][6] Along with Devi-Bhagavata Purana and Shakta Upanishads such as the Devi Upanishad, it is one of the most important texts of Shaktism (goddess) tradition within Hinduism.[8]
The Devi Mahatmyam describes a storied battle between good and evil, where the Devi manifesting as goddess Durga leads the forces of good against the demon Mahishasura—the goddess is very angry and ruthless, and the forces of good win.[9][10][11] In peaceful prosperous times, states the text, the Devi manifests as Lakshmi, empowering wealth creation and happiness.[12] The verses of this story also outline a philosophical foundation wherein the ultimate reality (Brahman in Hinduism) is female.[13][14][15] The text is one of the earliest extant complete manuscripts from the Hindu traditions which describes reverence and worship of the feminine aspect of God.[5] The Devi Mahatmya is often ranked in some Hindu traditions to be as important as the Bhagavad Gita.[16]
Devi Mahatmya - Wikipedia
The other goddesses mentioned in the Puranas are Parvarti, Lakhsmi
Shankara himself when he sets up the Smarta traditions sets up Devi as one of the five forms of Brahman. He also writes one of the principal devotional texts of the Shaktas, Soundarya lahri. After him, the tradition of identifying Devi as the Supreme Brahman is in vogue.
And frankly that is exactly what is being done today by making Jesus come and die in Kashmir as a Hindu saint. Upanisadic Hinduism believes in one God in many manifestation. Thus it constructs a puranic narrative connecting a new god to an old god and hence expands the reach of Hinduism outwards.
So you come to these conclusions because you lack scholarship. You are a very educated scientist, but you are not educated about the history of Hinduism. Even Aupmanyav is making the same mistake by saying Shiva, Durga are not mentioned in the Rig Veda therefore they pre-IVC gods. Now, as I have shown you, we can trace the history of both Shaivism and Shaktism back to as early as the Rig Veda. We are tracking a history of some 5000-10,000 years and we can see the clear development in the ideas. How Rudra became Shiva; Dyas-Pitra, the Skyfather, becomes become Ekam Sat(ONE) by the end of the Rig Veda and then Brahman in the Brahmanas and Aranyakas; how Pritivhi or earth-goddess becomes Aditi and then becomes Devi by the end of the Rig Veda. Then Maya and then Prakriti in the Upanishads. We can see how the pantheon of Hinduism has also changed over time, how in early times Indra is the major God but Vishnu is a minor God, but by late Vedic age Vishnu and Shiva are supreme. We can see how how new words come into vogue, old ones fall out of use. We can see how new gods are added e.g. Krishna, Rama, Durga, Hanuman, Parvati.
This is to be expected with a religion like Hinduism which has a extremely long history.
Hence, Shaktism is not an autonomous non-Vedic tradition, because we can trace its development from its medieval Tantra stage right back to the early Vedic stage continuously by each preceding historical period.
I will repeat again it is because of your ignorance and lack of research that you spread these false ideas. You are doing a disservice to Hinduism. Would you like it if I spread wrong ideas bout the sciences you have Phds in based on my wrong understandings? Nope. Similarly, I do not appreciate how based on your half knowledge of Hinduism, you are spreading wrong ideas about it.