If God is Moon than Shiva and Vishnu are like craters on that Moon. God has no name
The following verses from the Upanishads refer to the Concept of God:
Meaning: He is One only without a second.
[Chandogya Upanishad 6:2:1]
Na casya kascij janita na cadhipah
Meaning: Of Him there are neither parents nor lord.
[Svetasvatara Upanishad 6:9]
Na tasya pratima asti
Meaning: There is no likeness of Him.
[Svetasvatara Upanishad 4:19]
The following verses from the Upanishad allude to the inability of man to imagine God in a particular form:
Na samdrse tisthati rupam asya, na caksusa pasyati kas canainam.
His form is not to be seen; no one sees Him with the eye.
[Svetasvatara Upanishad 4:20]
He has no form as explained in Vedas like Yajurveda:
na tasya pratima asti
Meaning: There is no image of Him.
Meaning: He is bodyless and pure.
Brahma Sutra of Hinduism:
Ekam Brahm, dvitiya naste neh na naste kinchan
Meaning: There is only one God, not the second; not at all, not at all, not in the least bit.
Shiva is a collection of 11 Rudras described in Vedas/Upanishads while Vishnu is collection of 8 Vasus, further Surya/Sun God is worshipped with Gayatri and is collection of 12 Adityas. +1 Indra and +1 Brahma are total 33 koti devtas.
Puranas are Smritis that were created for Shudras and Women who had low intellect to understand reality, but Vedas are Shrutis and are highest-eternal to be studied by only Brahmins and learned Kshatriyas.
What is difference between Shruti and Smriti?
Between Smritis and Shrutis, Shrutis always speaks the truth
स्वतः पूर्णः परात्माऽत्र ब्रह्मशब्देन वर्णितः | अस्मीत्यैक्य-परामर्शः
तेन ब्रह्म भवाम्यहम् ||
Infinite by nature, the Supreme Self is described here by the word Brahman (lit. ever expanding; the ultimate
reality); the word asmi denotes the identity of aham and Brahman. Therefore, (the meaning of the expression is) "I am Brahman."
Aham Brahmasmi is the core of whole Vedas that is key for Kaivalya Moksha and leads to Sat Chida Ananda
Even Rama says so:-
I-i-15-17. Hanuman: Rama, sages speak differently: some say there is
only one kind of liberation. Others say it can be got by worshipping
your name and by the Taraka mantra at Kashi. Others speak of Sankhya-Yoga and Bhakti-Yoga, the enquiry into Vedanta-Vakyas etc.
I-i-18-23. Rama: Liberation is of four kinds: Salokya, Sameepya, etc. But the only real type is Kaivalya. Others are waste of human life.
Which Āstika schools mention the different types of Muktis?
What is the source of Sat Chit Ananda mantra?