"The Mayavadis say that the world created by maya is false, and that actually there is no living entity but only one spiritual effulgence. They further say that God is imaginary, that people think of God only because of ignorance, and that when the Supreme Absolute Truth is befooled by the external energy, maya, He becomes a jiva, or living entity. Upon hearing all these nonsensical ideas from the nondevotee, a devotee is greatly afflicted, as if his heart and soul were broken."
Caitanya-caritamrta, Antya lila 2:99
"....Vedanta refers to the essence of Vedic knowledge, and it is not a fact that there is nothing more than Sankaracarya's Sariraka-bhasya. There are other Vedanta commentaries, written by Vaisnava acaryas, none of whom follow Sri Sankaracarya or accept the imaginative commentary of his school. Their commentaries are based on the philosophy of duality. Monist philosophers like Sankaracarya and his followers want to establish that God and the living entity are one, and instead of worshiping the Supreme Personality of Godhead they present themselves as God. They want to be worshiped as God by others. Such persons do not accept the philosophies of the Vaisnava acaryas, which are known as suddhadvaita (purified monism), suddha-dvaita (purified dualism), visistadvaita (specific monism), dvaitadvaita (monism and dualism) and acintya-bhedabheda (inconceivable oneness and difference). Mayavadis do not discuss these philosophies, for they are firmly convinced of their own philosophy of kevaladvaita, exclusive monism. Accepting this system of philosophy as the pure understanding of the Vedanta-sutra, they believe that Krsna has a body made of material elements and that the activities of loving service to Krsna are sentimentality. They are known as Mayavadis because according to their opinion Krsna has a body made of maya, and the loving service of the Lord executed by devotees is also maya. They consider such devotional service to be an aspect of fruitive activities (karma-kanda). According to their view, bhakti consists of mental speculation or sometimes meditation. This is the difference between the Mayavadi and Vaisnava philosophies."
Caitanya-caritamrta, Adi lila 7:101
"One class of transcendentalists is called impersonalistic, Mayavadi. They are generally known as Vedantists, led by Sankaracarya. And there is another class of transcendentalists, called Vaisnavas, like Ramanujacarya, Madhvacarya, Visnu-svami. Both the Sankara-sampradaya and the Vaisnava-sampradaya have accepted Krsna as the Supreme Personality of Godhead. Sankaracarya is supposed to be an impersonalist who preached impersonalism, impersonal Brahman, but it is a fact that he is a covered personalist. In his commentary on the Bhagavad-gita he wrote, "Narayana, the Supreme Personality of Godhead, is beyond this cosmic manifestation." And then again he confirmed, "That Supreme Personality of Godhead, Narayana, is Krsna. He has come as the son of Devaki and Vasudeva." He particularly mentioned the names of His father and mother. So Krsna is accepted as the Supreme Personality of Godhead by all transcendentalists. There is no doubt about it."
Sri Isopanisad, Introduction
"When Sri Visnusvami, one of the four acaryas of the Vaisnava cult, presented his thesis on the subject matter of suddhadvaita-vada, immediately the Mayavadis took advantage of this philosophy and tried to establish their advaita-vada or kevaladvaita-vada. To defeat this kevaladvaita-vada, Sri Ramanujacarya presented his philosophy as visistadvaita-vada, and Sri Madhvacarya presented his philosophy of tattva-vada, both of which are stumbling blocks to the Mayavadis because they defeat their philosophy in scrupulous detail. Students of Vedic philosophy know very well how strongly Sri Ramanujacarya's visistadvaita-vada and Sri Madhvacarya's tattva-vada contest the impersonal Mayavada philosophy. Sri Caitanya Mahaprabhu, however, accepted the direct meaning of the Vedanta philosophy and thus defeated the Mayavada philosophy immediately. He opined in this connection that anyone who follows the principles of the Sariraka-bhasya is doomed. This is confirmed in the Padma Purana....
"My dear wife, hear my explanations of how I have spread ignorance through Mayavada philosophy. Simply by hearing it, even an advanced scholar will fall down. In this philosophy, which is certainly very inauspicious for people in general, I have misrepresented the real meaning of the Vedas and recommended that one give up all activities in order to achieve freedom from karma. In this Mayavada philosophy I have described the jivatma and Paramatma to be one and the same." How the Mayavada philosophy was condemned by Sri Caitanya Mahaprabhu and His followers is described in Sri Caitanya-caritamrta, Antya-lila, Second Chapter, verses 94 through 99, where Svarupa-damodara Gosvami says that anyone who is eager to understand the Mayavada philosophy must be considered insane. This especially applies to a Vaisnava who reads the Sariraka-bhasya and considers himself to be one with God. The Mayavadi philosophers have presented their arguments in such attractive, flowery language that hearing Mayavada philosophy may sometimes change the mind of even a maha-bhagavata, or very advanced devotee. An actual Vaisnava cannot tolerate any philosophy that claims God and the living being to be one and the same."
Caitanya-caritamrta, Adi lila 7:110
"Sankara's commentary on Vedanta-sutra, known as Sariraka-bhasya, is very much adored by the impersonalist scholars, but commentaries written on the Vedanta written from the materialistic point of view are completely adverse to the transcendental service of the Lord. Consequently Lord Caitanya said that direct commentaries on the Upanisads and Vedanta-sutra are glorious, but that anyone who follows the indirect path of Sankaracarya's Sariraka-bhasya is certainly doomed.
Lord Caitanya admitted that Sankaracarya was an incarnation of Lord Siva, and it is known that Lord Siva is one of the greatest devotees (a mahajana) of the Bhagavata school. There are twelve great authorities on devotional service, and Lord Siva is one of them. Why, then, did he adopt the process of Mayavadi philosophy? The answer is given in Padma Purana, where Lord Siva states:
pracchannam bauddham ucyate
mayaiva kalpitam devi
"The Mayavadi philosophy is veiled Buddhism." In other words, the voidist philosophy of Buddha is more or less repeated in the Mayavadi philosophy of impersonalism, although the Mayavadi philosophy claims to be directed by the Vedic conclusions. Lord Siva, however, admits that this philosophy is manufactured by him in the age of Kali in order to mislead the atheists. "Actually the Supreme Personality of Godhead has His transcendental body," Lord Siva states. "But I describe the Supreme as impersonal. I also explain the Vedanta-sutra according to the same principles of Mayavadi philosophy."
Teachings of Lord Caitanya, Chapter 19
".... Sankaracarya's belief is personal. Actually he is a covered personalist. He became impersonalist just to drive away Buddhism. All of India was Buddhist voidism. So, although a personalist, he had to keep pace with voidism by expounding impersonalism. There is very little difference between impersonalism and voidism, but because he had to bring Buddhists back to the Vedic cultural form, he adopted impersonalism. From the Padma Purana, it is learned that Sankaracarya is Lord Siva, and who can be a greater devotee than Lord Siva? Lord Siva is considered to be the foremost Vaisnava."
Srila Prabhupada Letter to Damodar, 11-12-70
"According to the Vedic teachings, anyone who does not accept the Vedic way of life, he is called atheist. Therefore, according to Vedantists, Buddhists are called atheist. Actually Buddha philosophy does not accept God, neither soul. They simply philosophize on the material elements, and they want to finish the material exis..., dismantle the material elements. Nirvana. So Caitanya Mahaprabhu has remarked that the Buddhists are honest. They frankly say that "We don't accept your Vedas." But the Shankarites, they are cheaters, because they are accepting Vedas, but on the basis of Buddha philosophy. That is cheating."
Srila Prabhupada Lecture on Srimad-Bhagavatam, 09-17-72, Los Angeles
Bhaktivedanta Book Trust. HDG A.C. Bhaktivedanta Swami Srila Prabhupada.