Manduka Upanishad has no assumptions whatever. It is an honest and bold inquiry into the truth. It rises above scripture.+

When one finds disappointment in religion, yoga, or mysticism he is in confusion and uncertainty, whether he is right or wrong. There is no certainty that he is proceeding on the right lines?" 

Thus doubts arise and the inquiring spirit comes and impels to search elsewhere for truth where it will not be possible even to have doubt. 

Some philosophers and theologians strongly believe in the existence of God. They use different names for Him, Her, or it. God can be Christ, Allah, or Brahma. They regard God as the creator of the whole universe. they think without potter the pot cannot be created. The doubt naturally arises in every seeker, if God is the creator if that is so, who created God. 

The truth is that from the ultimate standpoint, there is neither creator nor creation. The universe was not created by any person by whatever name you call Him or Her. There is no creator because there is no creation. Because the creation is a mere illusion created out of consciousness.

Consciousness is the only reality and all else is mere illusion. It is not the God-created creation but man-created God and creator and creation theory.

Remember:~

Sage Goudpada: he was the first historic Sage known to us to give a rational exposition of Advaita. He says that whatever is seen, whether external or internal, whether by ordinary persons or yogis is unreal.

Non-causality is of the highest importance; that is why Sage  Goudpada puts it at the end of his book and devotes 100 slokas to it whereas the other subjects get less than 50 slokas.

Manduka Upanishad has no assumptions whatsoever. It is an honest and bold inquiry into the truth. It rises above scripture.

Manduka Upanishad is not meant for all, as it is based entirely on reasoning. Hence, only a few will be able to understand and assimilate it.

Manduka Upanishad:~Atman is the highest Reality and its opposite: Note the word "and". Reality and illusion together make Brahman: nothing can be left out.  Page 51.

Brahman must be realized in the waking state when all objects are present to consciousness, otherwise, it is nonsense. Page 65: v.10.

"Sleep does not exist In Self-awareness”: This emphatically disproves the mystic use of sleep as an analogy for Brahman. Page 69.

This means that objects do not disappear, they are there, and yet they are non-dual. Disillusionment is not the same as appearance. Page 74. v. 17:

The essential message of Manduka is that the whole world, whatever is seen is only imagined.  points out that even though it is harder for them, still women can attain Brahman just as men. Page 351

"From their notion": Everybody has his own imagination about facts and starts from that, instead of discarding his personal idea and looking at the facts. Page 333. V. 83:

"Soundless and of infinite sounds"; means both the waking and sleep world must be known, and both objects and non-objects must be understood before the truth of Brahman is realized. Page 96. v. 29:

Manduka shows how one opinion may be used to contradict another so that both may be thrown away. Opinions are not for philosophy; they are as Ashtavakra says, merely thoughts; it wants the truth.

In deep sleep and anesthesia, you have non-duality but no Gnana. Therefore there must be discrimination along with non-duality. Otherwise sleeping dogs would be Gnanis. ~ (P.219)

Existence means existence in the sense of the Drik. When you reduce everything to consciousness, Drik, Gnana, or even Mind, giving up all imagination in truth it is unborn. You see a man's body come and go, but that is not the same as seeing him come and go, which you can never do. P.300. V.45.

Sage Goudpada 's 3^rd chapter is devoted to proving the existence of Atman to distinguish it from the changeable objects in this world, but in the final 4th chapter P.33, verse 83, he discards that position and rejects even the idea of Atmanic existence. He then declares we may assert nothing about it. Not even existence or nonexistence i.e. silence alone is demanded by the truth.

Remember:~

The yogi or mystic who sees or experiences God in his meditation which he takes as the ultimate but “how does he know it was the God?” That was only his inference. Can he say he knows God unless he is one with him? Mystics glibly say, "I know God," because I have seen him, and I had a conversation with him. Such claims are merely a hallucination.

The mystic who speaks of knowing, seeing, exiting a second being~ God, betrays thereby, that he is of limited intelligence; unable to grasp the Advaitic truth.

The seeker's attitude is: "If there is God ~ he has to prove it. If there is heaven ~ he has to prove it." Religious so-called philosophy dogmatically assumes the existence of the physicalized Gods.

How does the mystic know, that God who tells about himself in meditation is truthful! He may be hallucinating! His statements cannot be taken as truth. Supposing a mystic has a vision, which experience is true, but he must prove that it is what it purports to be because such vision is possible within the domain of the duality. 

From the nondualistic perspective, the duality is merely an illusion. Thus, whatever is seen known believed, and experienced within the domain of duality is merely an illusion

If one says God is light, others may also say it is light within. Again the light may take different colors. Then which color is correct? Others contend that God is sound and say they hear the OM sound inside in meditation, still others say God is the fragrant smell and that beautiful scent comes in meditation as the presence of God. 

All these differences of opinion can be endless and show mutual contradiction and general error, i.e., lack of certain truth.

If one sees a light he is seeing the second thing. Seeing the second thing is possible only in the domain of duality. In reality, no second thing exists other than the Soul, which is present in the form of consciousness.

God is the Spirit. All individual Gods belong to the domain of the illusory duality. Thus, all religious Gods are nothing, but imagination, based on the false self, within the false experience (waking)

There is nothing so absurd that people have not worshipped in religion and also sacrificial forms of worship so cruel they have not been indulged in. And every imaginable face has been given to God by artists. : ~ Santthosh Kumaar