While reading about atheistic Kapila, in the books of Śrīla Prabhupāda, you might wander, who that Kapila is, and what are his teachings. Well, here is one example of it, as far as whether soul is doer or the material nature is. By carefully studying just this point you will get a glimpse of malevolence of this credo, which poses as a spiritual one, and which deprives the soul of its functionality.
Adherents of atheistic Sāṅkha mistakenly separates two truths about the soul. They attribute to the soul (puruṣa) consciousness, but activities to matter (prakṛti) – ātmani ye ca bhidām. This is stated in Sāṅkhya-kārika 19-20, by Iswara Krishna a disciple of atheistic Kapila: "Because outward differences between souls are just superficial (because souls are covered by different qualities of nature), the true character of the soul is of witness, characterizes by that it is separated by it's indifference and state of inaction. Unconscious body, after the contact with soul, appears to have consciousness and it appears that the soul acts, although the soul is indifferent to the acting of the modes of nature."
Śrīla Vyāsadeva refutes this idea in Vedānta-sūtry 2.3.31-39, which starts with kartā śāstrārthavattvāt:
"The soul must be the performer of its actions, because the instructions of scriptures must have some meaning." Ācārya Baladeva Vidyābhūṣaṇa in his Govinda-bhāṣya explains: "Jīva, and not the modes of nature, is the doer. Why? Because instructions of the scriptures must have some meaning (śāstrārthavattvāt)."
Śrīla Prabhupāda explains in purport to Bhagavad-gītā 18.14: "The word adhiṣṭhānam refers to the body. The soul within the body is acting to bring about the results of activity and is therefore known as kartā, “the doer.” That the soul is the knower and the doer is stated in the śruti. Eṣa hi draṣṭā sraṣṭā (Praśna Upaniṣad 4.9). It is also conﬁrmed in the Vedānta-sūtra by the verses jïo ’ta eva (2.3.18) and kartā śāstrārthavattvāt (2.3.33). The instruments of action are the senses, and by the senses the soul acts in various ways. For each and every action there is a different endeavor. But all one’s activities depend on the will of the Supersoul, who is seated within the heart as a friend. The Supreme Lord is the supercause. Under these circumstances, he who is acting in Kṛṣṇa consciousness under the direction of the Supersoul situated within the heart is naturally not bound by any activity. Those in complete Kṛṣṇa consciousness are not ultimately responsible for their actions. Everything is dependent on the supreme will, the Supersoul, the Supreme Personality of Godhead."
In this connection naturally comes to the memory Bhagavad-gītā verse 3.27. Out of bad habit this ought not to be taken as contradiction, but rather as a support of very same point, because this verse discusses the attitude towards performing of action, either as a ego doer or doer in Kṛṣṇa consciousness. There should be no mistake done to take this verse to mean that soul is no doer. For lazy conditioned souls the terms of responsibility, liability, accountability and answerability brings about an uneasy feelings of higher authority who checks their actions. That is exactly what atheistic Sāṅkha profess to eradicate, resulting in spiritual and material lazyness, irresponsibility, carelesness and utter idiocy.