Swami Vivekananda: ~ Have only one idea of God.+

The Soul the  Self is not Christian, Jewish, Muslim, Hindu, Buddhist”, because it is ever formless, timeless, and spaceless existence.

In religion, there is no freedom to believe other than what it preaches.   Religious people consider the mythological stories as truth and not believing in mythological Gods is irreligious. The mythological God can exist within the domain of duality. From the Advaitic perspective,  the duality is merely an illusion.  Thus, whatever belongs to the illusion is bound to be a falsehood.

The religion declares one must believe that there is no other God but God propagated by the particular belief system.

The seeker has to deny the existence of such God based on the belief because the first one must realize what God really is.

People find some of the religious doctrines are very illuminating.  People who renounce the world and become a monk or sanyasi who leaves it all behind to find the truth of their true existence.

People think the events that happened in the mythological stories really happened the way they are described, and hallucinate about these stories.  

Swami Vivekananda: ~

The masses in India cry to sixty million Gods and still die like dogs. Where are these Gods?

Swami Vivekananda: ~ If religion and life depend upon books or upon the existence of any prophet whatsoever, then perish all religion and books! Religion is in us. No books or teachers can do more than help us to find it, and even without them, we can get all truth within. You have gratitude for books and teachers without bondage to them, and worship your Guru as God, but do not obey him blindly; love him all you will, but think for yourself. No blind belief can save you, work out your own salvation. Have only one idea of God - that He is an eternal help. 

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

Brihadaranyaka Upanishad: ~ The Self is indeed Brahman (God), but through ignorance, people identify it with intellect, mind, senses, passions, and the elements of earth, water, air, space, and fire. This is why the Self is said to consist of this and that and appears to be everything. 

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, 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 Self.   In reality, there is no duality, no differentiation. Only Atman exists.

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

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

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

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

When Upanishad itself declares: ~   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 non-dual reality (Chandogya Upanishad). 

Sage Sankara’s Supreme Brahman (God) is impersonal, Nirguna (without Gunas or attributes), Nirakara (formless), Nirvisesha (without special characteristics), immutable, eternal, and Akarta (non-agent). It is above all needs and desires. It is always the Witnessing Subject. It can never become an object as it is beyond the reach of the senses. Brahman is non-dual, one without a second. It has no other beside it. It is destitute of difference, either external or internal. Brahman cannot be described because the description implies a distinction. Brahman cannot be distinguished from any other than It. In Brahman, there is not a distinction between substance and attribute. Sat-Chit-Ananda constitutes the very essence or Svarupa of Brahman, and not just Its attributes. The Nirguna Brahman of Sage Sankara is impersonal.

Sage Sankara: ~"That which permeates all, which nothing transcends and which, like the universal space around us, fills everything completely from within and without, that Supreme non-dual Brahman  (Godin truth)."

Thus, truth realization is self-realization. Self-realization is God-realization.  God-realization itself is real worship. :~Santthosh Kumaar