Monotheism is defined as the belief in only one God and polytheism is defined as the belief in many Gods.+

Theism is in the traditional sense; it is the belief in at least one God. Monotheism is defined as the belief in only one God and polytheism is defined as the belief in many Gods.

Some organized religions follow monotheism where God is the supreme and none except him. These God-centric faiths follow a particular code of conduct that the ‘believer’ has to follow without questioning. He cannot question those rules, the life of the Sage, or the ultimate God. 

The individualized Gods God is isolated from nature and everything is God’s. Thus, the element of attachment to a name and gender, obstruction to free thinking and free will can be seen in all belief systems.

History speaks that in the past those who questioned the validity of this religious authority were exiled, killed, or termed as irreligious and condemned.

Theism, in this specific sense, conceives of God as personal, present, and active in the governance and organization of the universe.

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

When Bhagavad Gita says, that God is considered the all-pervading consciousness which is the basis of all the animate and inanimate entities and material then nothing has to be accepted as God other than consciousness. 

Lord Krishna says Ch ~V: ~ “Those who know the Self 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. 

The dualistic worship of "God” is only for the ignorant populace. The God in truth is only Atman, the innermost ‘Self’. In reality, there is no duality,, with no differentiation. Only Atman exists. 

The Vedas confirm God is Atman (Spirit), the ‘Self’. 

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)

Rig-Veda 1-164-46 and Y.V 32-1 clearly mention that God is “One.” 

Rig Veda says God is ‘ONE’ and God is Atman, then why believe and worship in place of the real God. 

Brihad Upanishad: ~ “If you think there is another entity, whether man or God there is no truth." 

Chandogya Upanishad says: ~ Sarvam khalvidam brahma ~ all this (universe) is verily Brahman. By following back all of the relative appearances in the world, we eventually return to that from which it is all manifest – the nondual reality.  

It proves the Vedic Gods are not the Gods with attributes because the Vedic God is a spiritual God. After all, Veda considers God as the Supreme Spirit which Atman. 

That is what Yajurveda says: not to worship the things which are part of the falsehood. 

Translation 1.

They enter darkness, those who worship natural things (for example air, water, sun, moon, animals, fire, stone, etc).

They sink deeper in darkness those who worship sambhuti. (Sambhuti means created things, for example, table, chair, idol, etc.) (Yajurveda 40:9)

Translation 2.

"Deep into the shade of blinding gloom fall asambhuti's worshippers. They sink to darkness deeper yet who on sambhuti are intent." (Yajurveda Samhita by Ralph T. H. Giffith pg 538)

Translation 3.

"They are enveloped in darkness, in other words, are steeped in ignorance and sunk in the greatest depths of misery who worship the uncreated, eternal Prakriti -- the material cause of the world -- in place of the All-pervading God, But those who worship visible things born of the Prakriti, such as the earth, trees, bodies (human and the like) in place of God 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." (Yajur Veda 40:9.)

So, Yajur Veda indicates that:-

They sink deeper in darkness those who worship idols and worship visible things, such as the earth, trees, and bodies (humans and the like) in place of God are enveloped in still greater ignorance. 

There was no individual God or temples and worship in the Vedic religion, which existed prior to Buddhism. 

Thus, the individualized Gods and temples must have been built later on, when the warships of the idol were introduced. Thus, the Vedic religion which existed in the past was free from idol and nature worship and idol worshiping rituals. 

Thus, the present day’s worship of individual Gods created things, nature, and humans is against Vedic teachings, and it looks like it has been fabricated and introduced by priestcraft. Since it, has passed on from one generation to the next it is hard for people to believe the truth of their own religion, because they are sentimentally and emotionally involved in it and they refuse to accept anything else other than their inherited beliefs. 

It is impossible to find and realize the truth via religion and scriptural study. Even Upanishads confirm this.:~Santthosh Kumaar