The Hindu belief systems are based on the false self. Thus their idea of god is mere belief based on their religious doctrine whereas in Advaita lord means Atman and Atman is Brahman. Brahman is ultimate truth or God.

The Vedic Culture and Vedas are complete in themselves but Hinduism which is non-Vedic belief system with all its ritual and conduct oriented practices has been contributed largely by the priests to suit their convenience!

Vedas are in Vedic language   which was a high class language. Rig Veda (excluding chapters II and X) were written before the Christian Era in Vedic language.  Vedic language is not Sanskrit.  It is the same language in which the Zoroastrian Scripture Zend Avesta is written – a form of Persian language.  All the other scriptures of India are written in Sanskrit.  These include Rig Veda Chapter II and X and the Upanishads, Brahmanas, Puranas and the Vedanta.  These were written during the Christian Era after the Thomas ministry. As the use of this language diminished, it became a tough language for the commoners. The priests, who were supposed to be expert of this language, translated it into Sanskrit language and manipulated the meanings in time and gradually, all the practices changed.

The DaVita, Vedanta borrows concept from Abrahamic religions, such as Eternal Damanation (of certain souls destined to hell forever) which goes against the belief of most Vedanta schools, which sate that soul attain liberation. 

 It looks like the creator creation theory is also borrowed from Abrahamic religion and on the base new belief system has been introduced giving it Vedic outlook and propagated all non-Vedic rituals and worships by someone in the past.  

St. Thomas is said to have come to India to spread Christianity in the first century AD. It first spread among the people of the Malabar coast and in areas near present-day Madras.

There is a total discontinuity in the concept of God before and after the entry of St, Thomas.  As one goes in deeper in to annals of religious history then we become aware of the fact that,    the Vedic gods were personifications of Nature and their worship essentially sacrifices to these Natural Forces to appease them.  All of a sudden by first century, we encounter Vedantas.  Vedanta literally means “End of the Vedas,” though it is today interpreted as "the essence of Vedas."

 Vedantas, which appeared as theological discourses, presents a supreme Godhead, “Para Brahman’.  Such an idea was not even remotely conceivable in the Vedic context.  

New Gods like Maheshwara and Vishnu appeared.  The concept of Maheshwara.  Vishnu means Sky or Heavens.   Vishnu simply means God of the Heavenlies or one who pervades everything.   Then we have the concept of incarnation – God taking flesh in human form to save humanity.  All these suddenly appeared after the entry of St, Thomas.

This was also the time when most of the Vedic gods passed into oblivion. Their place was taken by the trinity of gods, with Brahma as the creator, Vishnu the preserver and Shiva the destroyer. It is believed that when evil is rampant, various incarnations of Vishnu enter the world of men to save them. Krishna is one such 'avatar'. 

There are many contradictions, Brahma Vishnu and Maheshwar are the three main Gods but they are one. Brahma is the creator of this universe (Generator), Vishnu is responsible for the smooth conduct of the same (sustainer), & Maheshwar is Destroyer! But if you go and read Vishnu Purana, he is characterized as the supreme power.

Further, due to many caste and sub-caste prevailing in the society, some more rules and principles were added for the benefit of these priests. Can you imagine how would you get rid of the sin you committed by killing a cat? You will have to make a golden cat weighing equal to the dead cat and hand over this golden cat to the priest chanting for the purification of individual soul! Hinduism is different from Vedic religion.

Vedic religion was modified and reintroduced with new add-ons   by Sri, Sankara a great Advaita Master to uplift the Vedic culture and Santana Dharma , which were in ruins in the clutches of Buddhism. 18 puranas are introduced in the name of Veda Vyasa.

As one goes deeper in the annals of the history, it indicates the fact that somewhere someone has added the puranas in the name of Veda Vyasa the grand master of Vedas. It is impossible to accept and believe that Veda Vyasa authored and introduced puranas which has all conceptual gods because:- 

 In Vedas the God has been described as:- 

 

         Sakshi (Witness)

         Chetan (conscious)

         Nirguna (Without form and properties).

         Nitya (eternal)

         Shuddha (pure)

         Buddha (omniscient)

         Mukta (unattached).

Whereas Vedas reveals ONE GOD but Hinduism filled with 33crores of gods Vedas reveals God as Spirit (Atman or Brahman ) and no form whereas Hinduism worship god in the form of various non-Vedic  idols of god against Vedas .

  

Vedas say that God does not have any form and exist as light, but in Hinduism people idol worship with their inherited personal god. 

It indicates clearly all the gods with form and attributes are mere imagination based on the false self.  The ideas of conceptual gods are reality on the base of false self within the false experience.  Thus all the belief systems are based on the false self. Thus their idea of god is mere belief based on their religious doctrine. In Advaita lord means Atman and Atman means Brahman.