Hinduism or more frequently called "Sanatan Dharm" is the dominant religion, or Eternal way of Life. Hinduism is more of a guiding philosophy than a religion in true sense of the word. Hindu religious texts are Called as "Puranas", Hindu Mythology has several number of Puranas of which it is always said there are Eighteen most important called as "MahaPuranas". Its been said that their are three main deity viz. Brahma, Vishnu, & Shiva often know as "Tridev". Puranas usually give prominence to a particular deity; Mahapuranas are frequently classified according the three aspects of the divine Tridev. They are usually written by different sage of different time for the purpose to be easily understood by layman hence written in the form of stories related by one person to another. Puranas were originally written in Sanskrit Language but later on been translated by different sage and poet into their regional languages, hence the stories mentioned in Puranas are mostly common and related to each other but many times has a slight variation due to the change in Language, Culture, Point of View and Level of Understanding of Writers, for this reason the stories are not to be taken literally, but have symbolic meanings.
Concept
In Hindu cosmology the universe is created and destroyed in the timespan of 8.64 billion years. In layman's language it is believed that Lord Brahma Create the Universe, Lord Vishnu Take Care & Protect and for the purpose of Regeneration Lord Shiva Destroys the Universe. Hindu Cosmology describes the aspects of evolution, astronomy, astrology, creation etc. In Hindu Mythology for Creation of Universe there are many different stories from different Puranas and believes different form of deities as Para-Brahma (Para means “beyond” and brahma means “neuter” universal self or spirit, hence Para-Brahma means one who is highest beyond all conceptualisations)
Shiva Purana
As per the story in Shiv Purana at the very beginning when there was no universe not even the time cycle, nothing except the complete darkness. In that darkness with the sound of OM (Omkar) a bright divine light appeared and Para-Brahma Lord Shiva Manifested from it (sometimes also believe Shiva Manifested with his Shakti, also called as “Adi-Parashakti” meaning mother of Universe, by whom each and everything on this universe exist). Later on Lord Vishnu Manifested and Lord Brahma sitting in his Lotus was born through Vishnu's navel. Brahma on the wish of Lord Shiva starts creation of universe.
Vishnu Puranas
Vishnu Purana / Bhagavata Purana consider MahaVishnu or Narayana as Para-Brahman Supreme God who creates unlimited universes and enters each one of them as Lord of Universe, in some beliefs Lord Vishnu is non-different from the Trimurti. At the beginning of time he manifested in the three different forms all are different individual but of same personality. Vishnu Purana states one which is created has to come to an end, where there is birth their is death for the purpose of Creation (Life) he appeared as Lord Brahma with the Rajas Guna (quality of activity) in him, Lord Shiva for the purpose of Destruction (end, destruction not to be taken as end instead a process of new beginning) with Tamas Guna (quality of darkness) in him and between the time cycle of creation and destruction he does the protection (maintenance) as Lord Vishnu or Narayana with Sattva Guna (quality of goodness) in him.
Devi Mahatmyam
Another Hindu Text Devi Mahatmyam (also known as Durga Saptashati) which is a set of 700 verses arranged in 13 Chapters is a part of Markandeya Purana, it is believed most important by the followers of Shaktism. Devi Mahatmyam states Devi / AdiShakti as the central key to the creation of universe. She is the Divine Mother and possessor of all the existing powers in the Universe. She is the reason behind Manifestation of All three Lords, she is the power that induces Lord Vishnu’s deep slumber on the waters of the cosmic ocean prior to the creation of Universe. Here Devi inspires Lord Brahma to Create Universe and later on has a series of stories.
ISKCON Belief
Some of my SCGM & ISKCON Friends having a very deep concept for this, explained me that Lord Krishna is the Supreme Godhead (not to be confused with Lord Krishna who took birth some five thousand year ago) who is Omnipresent who is the source of all sources and for the affairs of material creation he expands himself into different forms. Maha-Vishnu is just a plenary portion of Supreme Lord Krishna, and later Maha-Vishnu manifest into different forms. The various forms of the Lord are existing eternally in the spiritual world and their descent to the material world is called avatar (literally, one who descends). The various incarnations of Vishnu among which are included Krishna and Balarama sons of Vasudev. Although Krishna appears to be one of the avatars, He is in fact the Original Personality of Godhead, and that all other incarnations are His plenary expansions, Krishna is the complete whole, and when He descends, all plenary expansions and incarnations, including Maha-Vishnu, descend along with Him in His transcendental body.
Brahmanḍ Purana
Some Puranas states that Lord Brahma was born through Lord Vishnu’s Navel sitting in his Lotus, some other states Brahma is self-born in the lotus flower. Another legend says that Brahma was born in water, or from a seed that later became the golden egg known as “Hiranyagarbha” From this golden egg, Brahma, the creator was born. The remaining materials of this golden egg expanded into the Brahmanḍa or Universe. There is a story for "Sharsa Brahma" (Sharsa often referred as thousand) hence the concept of multiple universes as every Brahma creates his Bhramand (Universe) for one (or one hundred) Brahma year.
All the three main deities took over different work and possess different powers and with them have their female counterpart in the form of Shakti. Some belief them just as Power (Shakti) others consider them as Wife or Consort and its obvious wife is often called as better half. In Shiv Mahapuran especially for Lord Shiva there is a concept of Prakriti and Purush while Purush is the Male Deity and Prakriti being his Female Counterpart, once taken a form of “Ardhanarishvara” (Lord who is half women) and also states that Purush is powerless without Prakriti.
Conclusion
At the end whoever is believe as a Main Deity conclusion concept is:
- Lord Brahma – is the Creator of Universe, Gives Life (his Shakti is in form of Mata Saraswati, Goddess of Knowledge, Wisdom, Music, Art and Learning, She is cosmic intelligence, cosmic consciousness, and cosmic knowledge)
- Lord Shiva – is the Destroyer / Transformer (his Shakti is in form of Mata Parvati / Durga goddess of power, love, and spiritual fulfilment; She also depicts the transformational power of divinity, the power that dissolves multiplicity in unity)
- Lord Vishnu – the Protector, who take care to run the universe smoothly (his Shakti is in form of Mata Lakshmi Goddess of wealth, fertility and represents all kinds of prosperity, glory, magnificence, joy, exaltation, and greatness.)