Emergence of various forms Deities in Hinduism

Emergence of various forms Deities in Hinduism
Hinduism recognizes the diverse aspects of personalities and personal preferences. Worshipping or prayer of god has its root in human desires.  Various deities in Hinduism address the different aspects of human desires. For instance, Lakshmi ji is worshipped for wealth & prosperity, Sarasvati ji is worshipped for knowledge & various discipline of art, Durga ji is worshipped for power & valor, Ganesha ji is worshipped mainly to overcome obstacles, Hanuman ji is worshipped mainly for strength,   Shiva represents austerity and so on. Hence, the Hinduism offers more than one options for worshipping and creating personal bond. This can be seen in parallel with the growth of general management system to specialized management system in corporate world for better results.
 
Since Vedic times, many forms of this divinity have been idolized such as deities of nature (Indra, Agni, Soma, Surya etc.); 33 koti deities (eight Vasus, eleven Rudras, twelve Adityas, Indra and Prajapathi Brahma); Trimurti (Brahma, Vishnu & Shiva), Panchparmeshvar (Shiva, Vishnu, Devi or Parvati, Surya and an Ishta Devata) and Vaishnava Avtars (mainly Rama & Krishna).
 
However, Hinduism fundamentally, establishes that there is only Brahman or one all-pervasive God or cosmic consciousness which energizes the entire universe and also deities.
 
Emergence of various forms of deities is discussed as below:
 
Vedic Deities:

1. During Vedic period (over 5000 years ago), people did not worship images or idols but gods of nature. Vedic people did not build any temples to house their gods.
2. There was no supreme deity. The gods in the Rig-Veda fall into two categories: the devas – who were gods of nature – such as the weather deity Indra (who is also the King of the gods), Agni ("sacrificial fire"), Usha ("dawn"), Surya ("sun") and Apas ("waters") on the one hand, and on the other hand the asuras – gods of moral concepts – such as Mitra ("contract"), Aryaman (guardian of guest, friendship and marriage), Bhaga ("share") or Varuna, the supreme Asura (or Aditya). Devas are characterised as Younger Gods while Asuras are the Older Gods.
3. In later Vedic texts, the Asuras become demons. Gradually, dominance of four-fold godhead namely Indra (associated with storm), Agni, Soma (plant of immortality i.e. amurta) and Surya (or aditya) emerged. Extensive hymns were consecrated to these gods in the Rig Veda.
4. Philosophically, Vedic gods represent symbols of inner self (antahkaran) such as Sun symbolises to intellect, Agni to volition, Soma to feelings etc.

33 Koti Deities
In Brihadaranyaka Upanishad, it is mentioned that 33 koti deities as the important ones, namely eight Vasus, eleven Rudras, twelve Adityas, Indra and Prajapathi Brahma. These gods belong to different sphere in creation.
Note:
Please also see related article on my website named as “what is God in Hinduism” published on 19.06.2018 under the category “Principles”.
 
Trimurti or Trinity Deities
The triad (trimurti or trinity or Brahma, Vishnu & Shiva) appears in Maitrayaniya Upanishad, for the first time. From the 1st century CE a new type of worship known as Bhakti or devotional Hinduism spread across the Indian sub-continent, and the old Vedic gods were replaced in importance by deities like Shiva, Vishnu, Brahma, and Devi. Their worship required temples where the devoted could offer their thanks which led to construction of elaborate temples.
 
 Supreme Brahman:

1. Major Upanishads like Brihadaranyaka, Ishavasya, Chandogya, Katha, Kena, Aitareya, do emphasize on the knowledge of Brahman as essential to liberation.
2. Sri Adi Shankaracharya (788-820) established Advaita (Non-duality of Supreme Brahman) interpretation of Vedanta which has its roots at least to Gaudapada (600 CE). 

 
Panch-Parmeshwar

1. Five deities being Shiva, Vishnu, Devi or Parvati, Surya and an Ishta Devata such as Kartikeya or Ganesha or any personal god of devotee's preference. It became popular in medieval period which has been attributed to Adi Shankara, the 8th century CE.
2. The Puranas provide insight into the aspects of idol-worship, festivals and devotions. There are 18 Mahapuranas and an equal number of subsidiary Puranas or Upa-Puranas and many 'sthala' or regional Puranas. Of the 18 major texts,
   1.         six glorify Vishnu; six glorify Brahma; and six glorify Shiva viz. Vaishnava aspects - Vishnu Purana, Naradiya Purana, Bhagavat Purana, Garuda Purana, Padma Purana, Varaha Purana;
   2. Brahma as central deity - Brahma Purana, Brahmanda Purana, Brahma-Vaivarta Purana, Markandeya Purana, Bhavishya Purana, Vamana Purana;
   3. Shaivite aspects -  Matsya Purana, Kurma Purana, Linga Purana, Shiva Purana, Skanda Purana and Agni Purana.
3. In Markandeya Purana, glorification of goddess is recognized under all major aspects. This led to traditions of Vaishnavism, Shaivism, Shaktism, and Smarthism.
4. The Vaishnavism tradition is known for the loving devotion to an avatar of Vishnu (often Krishna), and it has been key to the spread of the Bhakti movement.
5. In the Shaivism traditions, the followers revere the Shiva as Supreme Being.
6. In the Shaktism tradition, feminine and Adi Parashakti is supreme.
7. In the Smarthism or Smarta tradition treat all the five deities treated as equal – Vishnu, Shiva, Ganesha, Surya and Devi (Shakti).

Vaishnava Avtars

1. During medieval period, Philosophers such as Ramanujacharya, Madhvacharya, Nimbarkacharya, and Vallabhacharya started Various Vaishnava Sampryadaya to worship of Sita-Rama and Radha-Krishna as Sagun Upasna. Even, Adi Shankara who believed to be advocated Jnana marg, also emphasized the importance of devotion and wrote Bhaja Govindam of 33 verses.
2. Vaishnava-inspired scholars authored 14 Vishnu avatar-focused Upanishads that are called the Vaishnava Upanishads. These Upanishads quote the texts included in the Brihadaranyaka Upanishad, Chandogya Upanishad, Katha Upanishad, Isha Upanishad, Mundaka Upanishad, Taittiriya Upanishad and others.
3. The Bhagavad Gita is a central text in Vaishnavism, and especially in the context of Krishna. The two Indian epics, the Mahabharata and the Ramayana also present Vaishnava philosophy and culture.
4. During the 9th-17th centuries, Bhakti poets such as Alwars, Raidas, Narsigh Mehta, Haidas, Meera Bai, Namdev, Ramananda, Surdas, Tulsidas, Eknath, Tyagaraja, Chaitanya Mahaprabhu and many others influenced the expansion of Vaishnavism. They wrote a large number of Bhajans (poetries) in the glory of Parmatama and taught the religion of love and kindness to society.

Note:
Please also see related articles on my website named as “Vaishnava Bhakts” published on 02.03.2018 under the category “Deities, Philosophers and Bhakts” and “Bhakti Yoga” published on 07.03.2018 under the category “Philosophy”.
 
One Supreme God taking multiple forms in Deities

1. Shree Krishna (in chapter 7, verse 21 of Bhagavad Gita) has clarified that whatever deity a devotee chooses to worship with reverence (out of craving for some worldly object), I stabilize the faith of that particular deity/form. He explains that ignorant persons do not understand that the powers of the deities are derived from Brahman i.e. supreme God and Brahman himself gives them the desired fulfilment. Further, he (in verses 9.18, 10.21-23 and 11.15) asserts that the triad or trinity is manifestation of one Brahman.
2. Shree Krishna further, asserts on Vedic Gods (in chapter 10 of Bhagavad Gita), he is Vishnu among the twelve Adityas, Shiva among eleven Rudras, Agni among eight Vasus, the radiant sun among the luminaries, the moon, the lord of the stars, the Indra and essence of so many things.

 
Hence, Nirakar & Nirgun Brahman takes various forms of deities to satiate the needs & desires of human being.