These impersonalists of the present age declare themselves to be the followers of Sripad Sankaracarya, but even if Sankaracarya himself happened to appear, he would be astonished to see his so-called followers. In fact, these impersonalists are all atheists and materialists. They have nothing to do either with the actual brahmavada school of Sankaracarya or with the bhagavata sampradaya represented by the Vaisnava acaryas.
The impersonal conception of the Absolute Truth, as propounded by the so-called brahmavada school, falls short of spiritual progress from its first step. Sankaracarya’s impersonal conception of brahmavada had some meaning because he emphasized renouncing material activities. His ideal example of renunciation, as personally practiced and taught by him, has great significance for the demoniac people of the age of Kali, but the present impersonalists do not follow Sankaracarya or the sastra. They do, however, preach something that is not only absurd from all spiritual points of view, but is the start of material enjoyment, which they try to cover with the red garments of renunciation. These so-called followers of Sripad Sankaracarya are condemned by Sankaracarya himself, because they have taken the red dress simply for the matter of filling their bellies.
The atheistic impersonalists have done tremendous harm to the potential for spiritual advancement of the people in general. Therefore, the impersonalists have become the principal target of reformation for the peaceful sankirtana movement of Lord Caitanya.
Excerpted from the Bhaktivedanta VedaBase 2011.