Sage Sri, Sankara criticized severely the ritualistic attitude and those who advocated such practice.+

People are not prepared to verify the facts about their own religion they are unable to understand and assimilate the Self-knowledge or Brahma Gnana or Atma Gnana. Until one has an urge to know the truth and prepares the ground properly, and he is consistent in his efforts to know the truth, he will not be receptive to receive Self-knowledge or Brahma Gnana or Atma Gnana.

In India, people think that religion as a stepping stone to higher truth but it is not so because religion is based on the false self (waking entity or ego) within the false experience (waking or world).

People of small intelligence follow religion and believe that the world was created by God. But how do they know that He did so? When a pot is created one can see both pot and its maker, but not in the case of the world. Then there is the question which nobody has answered till now, viz. Why did He create all these evils, these sufferings? Even a father would never do that. If He did so, assuming that God did create, then what sort of an evil God is He! 

All religions which begin with "God created the world," are fit only for children. It is a lie; it is inconsistent and fit only for ignorant people.

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) VivekaChudamani v 56, pg 25

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, 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. 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) 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 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. 

Mundaka Upanishad: ~   The rituals and the sacrifices described in the Vedas deal with lower knowledge. The sages ignored these rituals and went in search of higher knowledge. ... Such rituals are unsafe rafts for crossing the sea of samsara, of birth and death. Doomed to shipwreck are those who try to cross the sea of samsara on these poor rafts. Ignorant of their own ignorance, yet wise In their own esteem, these deluded men Proud of their vain learning go round and round Like the blind led by the blind.

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)

It is clear that liberation cannot be the result of good works, for Sruti itself declares that there is no hope for immortality by means of wealth.  (Verses -7)

Neither sacred baths nor any amount of charity nor even Hundreds of pranayamas* can give us the knowledge about our own Self.  The firm experience of the nature of the Self is seen to proceed from inquiry along the lines of the salutary advice of the wise. (Verses- 13)

One of Sage Sankara’s missions was to wean people away from the ritualistic approach advocated by Mimamsakas and to project wisdom (Jnana) as the means of liberation in the light of Upanishad teachings. Sage Sankara criticized severely the ritualistic attitude and those who advocated such practices. However, the texts that combined rituals with wisdom (jnana_karma_samucchaya) more in favor of the Mimamsaka position came onto vogue, projecting  Sage Sankara as the rallying force of the doctrine.

Self-Knowledge or Brahma Gnana or Atma Gnana puts an end to ignorance, which is the cause of experiencing the duality as reality. Experiencing waking experience (duality), as reality is the cause of misery.  

It is necessary for the seeker to realize the existence of the formless witness of the three states, to overcome ignorance.  Only when the seeker overcomes the ignorance, realize the fact that ‘I’ is not the Self,  but the witness of the ‘I’, which is the Soul, is the true Self. The seeker has to learn to view and judge the three states on the base of the Soul, the Self only then the truth will start unfolding. 

Sage Sankara varied his practical advice and doctrinal teaching according to the people he was amongst. He never advised them to give up their particular religion or beliefs or metaphysics completely; he only told them to give up the worst features of abuse: at the same time, he showed just one step forward towards the truth.  Sage  Sankara was extremely precise and careful in his choice of words. 

Sage Sankara' gave religious, ritual, or dogmatic instruction to the populace, 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 believed that those of superior intelligence, have no need of this idea of divine causality, and can, therefore, dispense with Sruti and arrive at the truth of Non-Dualism by pure reason. 

Sage Sankara’s Supreme Brahman (God)  is Nirguna (without the Gunas), Nirakara (formless), Nirvisesha (without attributes), and Akarta (non-agent). He is above all needs and desires. 

Sage Sankara says, "This Atman is self-evident. This Atman or Self is not established by proofs of the existence of the Self. It is not possible to deny this Atman, for it is the very essence of he who denies it. Atman is the basis of all kinds of knowledge. The Self is within, the Self is without, the Self is before and the Self is behind. The Self is on the right hand, the Self is on the left, the Self is above and the Self is below":~Santthosh Kumaar