There is a clear-cut idea in the scriptures, what's supposed to be God.+

First, one has to realize what God is supposed to be. Without knowing what God is in truth, truth-realization or God-realization is impossible. God is not different from Atman nor is Atman different from God.

The God in truth is only Atman, the Self. In reality, there is no duality, no differentiation. Only Atman exists.

Holding the belief as God keeps the Soul, the Self permanently in ignorance. The ignorance keeps the Soul permanently in the prison of dualistic illusion. Illusion makes the Soul remain in the domain of form, time, and space. In the domain of form, time, and space the experience of birth, life, death, and the world is experienced as a reality.

If the seeker wants to realize the truth, then he has to discard all the religious beliefs and yogic practices, and scriptural studies. Nothing is needed in pursuit of truth other than an intense urge and receptivity to realize the truth, which is beyond form, time, and space.

That is why Sage Sankara: ~ VC -Let erudite scholars quote all the Scripture, let Gods be invoked through sacrifices, let elaborate rituals be performed, let personal Gods be propitiated---yet, without the realization of one‘s identity with the Self, there shall be no liberation for the individual, not even in the lifetimes of a hundred Brahmas put together (verses-6)

Sage Sankara said:~ -Neither by the practice of yoga nor philosophy, nor by good works nor by learning, does liberation come, but only through the realization that Atman and Brahman are one in no other way. (1) Vivekachoodamani v 56, pg~25

Sage Sankara’s wisdom is nothing to do with religion and yoga. There are two kinds of audiences - the ordinary ones who desire the transitory heaven and other pleasures obtained as a result of ritual sacrifices, and the more advanced seeker who seeks to know the truth beyond the form, time, and space. Religion and yoga are meant for the first audience, to help lead their followers along the way. Sage  Sankara’s Advaitic wisdom, with its emphasis on the Advaitic wisdom, is meant for those who wish to go beyond such transient pleasures.

First, you must know what God is supposed to be. There is a clear-cut idea in the scriptures, of what is supposed to be God. And what not to worship in place of God then why worship the belief of God, which is not God.

That is why Lord Krishna Says Ch ~V: ~ “Those who know me in truth.". The last two words (tattvataha) are usually ignored by pundits, but they make all the difference between the ordinary concept of God and the truth about God.

Bhagavad Gita: ~ Brahmano hi pratisthaham ~ Brahman (God in truth) is considered the all-pervading consciousness, which is the basis of all the animate and inanimate entities and material. (14.27)

Rig Veda: ~ The Atman is the cause; Atman is the support of all that exists in this universe. May ye never turn away from the Atman the innermost self. May ye never accept another God in place of the Atman nor worship other than the Atman?" (10:48, 5)

Yajurveda – chapter- 32:~ God is Supreme Spirit has no ‘Pratima’ (idol) or material shape. God cannot be seen directly by anyone. God pervades all beings and all directions. Thus, Idolatry does not find any support from the Vedas.

It is for every seeker who is seeking truth must first know what God is supposed to be in actuality according to Vedas and Upanishads and reject all non-Vedic Gods to realize the Atman is  God in truth.

Bhagavad Gita Chapter:~ “All those whose intelligence has been stolen by material desires, they worship many Gods. (7- Verse -20)

Brihadaranyaka Upanishad: ~ Brahman (God in truth) is the form of the Athma, and it is indeed Athma itself’.

Thus, it refers to a formless and attributeless God, which is the Atman (Soul), the innermost ‘Self’ within the false experience. Thus, it indicates clearly all the Gods with form and attributes are mere imaginations based on the false ‘Self’. Thus Atman or Soul, the ‘Self’ is God in truth.

The Vedas do not talk about idol worship. In fact, till about 2000 years ago followers of Vedism never worshipped idols. Idol worship was started by the followers of Buddhism and Jains. There is logic to idol worship. Vedas speak of one God that is the supreme ‘Self’ i.e. Atman or Soul but Hinduism indulges in worshiping 60 million Gods.

It indicates clearly all the Gods with form and attributes are mere imaginations based on the false ‘Self’.

The Brihadaranyaka Upanishad:~ "He who worships the deities as entities entirely separate from him does not know the truth. For the Gods, he is like a pasu (beast)". (1. 4. 10)

A great majority of Hindus are not in contact with their religious history therefore, they believe their inherited beliefs as the ultimate truth.

People, who worship the belief of God, are hallucinating that they become one with such God.

Vedas itself says: May ye never accept another God in place of the Atman nor worship other than the Atman? Thus, to know the real God Self-realization is necessary. Self-realization is God-realization. Self-realization itself is real worship. 

Remember:~

The Soul, the ‘Self is the Infinite God. 

The Soul is the Self. God is the Soul, which is present in the form of consciousness. God is the fullness of the consciousness without the illusory division of form, time, and space. Therefore, there is nothing apart from it. 

God is Self-evident. God is not established by extraneous proofs. It is not possible to deny God because God is the very essence of the one who denies it. God is the basis of all kinds of knowledge, presuppositions, and proofs. God is within the universe in which you exist, the God is without the universe in which you exist.

Ishopanishad says: ~ “They are steeped in ignorance and sunk into the greatest depth of misery who worships the matter, instead of the All-Pervading God and those who worship things born of matter like trees, animals, man, etc. are sunk deeper in misery." 

Vedas says: ~  ‘One should never accept another God in place of the Atman nor worship other than the Atman. If one, worships any other God in place of Atman, are enveloped in still greater darkness, in other words, they are extremely foolish, fall into an awful hell of pain and sorrow, and suffer terribly for a long time."

All is consciousness. The whole universe is consciousness. From consciousness, the universe comes. When the universe disappears, the consciousness still remains without form, time, and space.

The consciousness, the God is Self-evident. It is not established by extraneous proofs. It is not possible to deny God because God is the very essence of the one who denies God. God is the basis of all kinds of knowledge, presuppositions, and proofs.

All those whose intelligence has been stolen by ignorance believe in non-Vedic Gods.

The Vedas talk about Brahman (God) which refers to the ultimate truth or ultimate reality or Advaita. The consciousness is the Advaita or the ultimate truth, therefore, the consciousness is the ultimate truth or Brahman or God in truth. Brahman is Advaita(nondual). 

So, it clearly indicates the so-called Gods worshipped in the temples today are not Vedic Gods. Vedas bars worshiping such Gods. 

Why worship and glorify the Gurus and Yogis when Vedas bar human worship because God cannot be seen directly by anyone. : ~ Santthosh Kumaar