Upanishads ridicules the worshiper of deities as a dim-witted person no better than a beast.+

The orthodoxy has to be dropped if one has chosen the path of wisdom. The orthodoxy is a great hindrance in the pursuit of truth because it makes the inborn samskara(I) more and stronger. Till this inborn conditioning prevails it is impossible to grasp, assimilate and realize the non-dual truth. The orthodoxy is egocentric and egocentricity is the greatest obstacle in the path of truth.  

 The orthodoxy indulges in all non-Vedic rituals and because of add-ons and adulteration and such rituals lead one nowhere and it is a waste of time and effort.   Thus orthodoxy is not for those who are seeking truth nothing but the truth.  Mixing orthodoxy and preaching non-duality is a  foolish venture.

Rituals and theories are not meant for those who are searching for the Brahman or ultimate wisdom.  

That is why Gaudapada says:~ the merciful Veda teaches karma and Upasana to people of lower and middling intellect, while Jnana is taught to those of higher intellect.

Thus,  the Orthodox Advaita is not meant for those seeking ultimate truth or Brahman but orthodoxy is meant for people of lower and middling intellect.  Those who are seeking Advaitic truth have to drop orthodoxy in order to realize the ultimate truth or Brahman.

Advaitic orthodoxy blocks the realization of ultimate truth or Brahman. Thus, if one wants Advaitic truth or wisdom he has to drop the path of Advaitic orthodoxy, which is meant for the traditionalists who take the practical life within the practical world as a reality. 

The Advaitic path of wisdom is nothing to do with religion, scriptures,  and conceptual Gods.  The self, which is the form of consciousness is Brahman or ultimate truth, is beyond form, time, and space or birth, life, death, and the world.  Thus one has religion, scriptures and conceptual God has to be bifurcated from the path of Gnana or Advaitic wisdom. 

The rituals mentioned in the karmakanda of the Vedas are sought to be negated in the jnanakanda which is also part of the same scripture. While the karmakanda enjoins upon you the worship of various deities and lays down rules for the same, the jnanakanda constituted by the Upanishads ridicules the worshipper of deities as a dim-witted person no better than a beast.

This seems strange, the latter part of the Vedas contradicting the former part. The first part deals with karma, while the second or concluding part is all about Jnana. Owing to this difference, people have gone so far as to divide our Scriptures into two sections: the Vedas (that is the first part) to mean the karmakanda and the Upanishads (Vedanta) to mean the jnanakanda.

Lord teaches us in the Gita and in it, he lashes out against the karmakanda. 

The essence of Mundaka is: ~  Do not be satisfied with rituals, yoga, etc. which are good in their own way but inquire. Into what? Brahman and Atman are things you can never see. So do not inquire into them. Inquire into the world around you, which you can see. Science tells you it is passing away every second. Everything is dying repeatedly. Where is it going? Thus, you follow up your inquiry into what you can lay your hands on. How can you inquire into Atma which you cannot see? So first we deal with the known and seen, this inquiry leads up to the unknown in the end.

Mundaka Upanishad condemns rituals.  The Para or Higher knowledge is the knowledge of the Supreme Being while the Apara or Lower Knowledge is that of following sacrificial rites and ceremonies. (1/2/ 1 – 6)

Sage Sankara gave religious, ritual, or dogmatic instruction to the mass but pure philosophy only to the few who could rise to it. Hence,  the interpretation of his writings by commentators is often confusing because they mix up the two viewpoints. Thus,  they may assert that ritual is a means of realizing Brahman, which is absurd. 

Sage Sankara:~ (11) As regards the rituals, Sage Sankara says, the person who performs rituals and aspires for rewards will view himself in terms of the caste into which he is born, his age, and the stage of his life, his standing in society, etc. In addition, he is required to perform rituals all through his life. However, the Self has none of those attributes or tags. Hence, the person who superimposes all those attributes on the changeless, eternal Self and identifies Self with the body is confusing one for the other; and is, therefore, an ignorant person. The scriptures dealing with rituals, rewards, etc. are therefore addressed to an ignorant person. -Adhyasa Bhashya

Sage Sankara:~ (11.1) This ignorance (mistaking the body for Self) brings in its wake a desire for the well-being of the body, aversion for its disease or discomfort, fear of its destruction, and thus a host of miseries(anartha). This anartha is caused by projecting karthvya(“doer” sense) and bhokthavya (object) on the Atman. Sage Sankara calls this adhyasa. The scriptures dealing with rituals, rewards, etc. are, therefore, he says, addressed to an ignorant person.-Adhyasa Bhashya

Sage Sankara:~ (11.2) In short, a person who engages in rituals with the notion “I am an agent, doer, thinker”, according to Sage Sankara, is ignorant, as his behavior implies a distinct, separate doer/agent/knower; and an object that is to be done/achieved/known. That duality is avidya, an error that can be removed by vidya.-Adhyasa Bhashya

Sage Sankara: ~ (12) Sage Sankara affirming his belief in one eternal unchanging reality (Brahman) and the illusion of plurality, drives home the point that Upanishads deal not with rituals but with the knowledge of the Absolute (Brahma vidya) and the Upanishads give us an insight into the essential nature of the Self which is identical with the Absolute, the Brahman.-Adhyasa Bhashya

Sage Sankara: ~ Atman, the innermost self is verily Brahman (God), being equanimous, quiescent, and by nature absolute Existence, Knowledge, and Bliss. Atman is not the body that is non-existence itself. This is called true Knowledge by the wise. 

So, they clearly indicate rituals and theories are not meant for those who are searching for higher knowledge or wisdom.   The path of wisdom is the only means. 

All the orthodox Advaitins indulge and immersed themselves in ritualistic oriented lifestyles and follow the path of karma and Upasana which is meant for lower and middling intellect and not for realizing the Advaitic truth.  

Many chose these orthodox scholars as their Gurus. But these Gurus are good to learn the conceptual Advaita meant for those orthodox who believe their conduct-oriented lifestyle leads to Moksha (liberation).   

The orthodox Advaita is not the means to acquire Self –knowledge or nondual wisdom.  Those who are seeking the truth have to do their own homework in order to acquire Self-knowledge or Brahma Gnana or Atma Gnana. :~Santthosh Kumaar