Spiritual knowledge means to become Kṛṣṇa conscious. This is the sum and substance, to understand Kṛṣṇa, what He is, not that concocting, manufacturing that, "Kṛṣṇa is this. Kṛṣṇa is that." No. As Kṛṣṇa says, as śāstra says what is Kṛṣṇa, you have to understand it like that. So sādhu śāstra guru vākya. It is said that we have to accept knowledge through saintly person. Through śāstra and guru we have to understand. So Kṛṣṇa is accepted by all the sādhus and ācāryas. Śaṅkarācārya, Rāmānujācārya, Madhvācārya, Nimbārka, Viṣṇu Svāmī, Śrī Caitanya Mahāprabhu—all of them accepted Kṛṣṇa, the Supreme Personality of Godhead. So ācārya means one who has learned, taken knowledge from the śāstra, authoritative śāstra, Vedas. Therefore in the Bhagavad-gītā it is recommended, ācāryopāsanam. If you want real knowledge, then you must take knowledge from the ācāryas or the ācārya-paramparā. Then there is knowledge. Otherwise it is ignorance.
So under the circumstances, whatever Kṛṣṇa says, Bhagavān says . . . śrī-bhagavān uvāca, mayy āsakta-manāḥ pārtha. The real business is to increase your attachment for Kṛṣṇa. This is your real business. How we can increase our attachment for Kṛṣṇa, that is explained by Kṛṣṇa. So mayy āsakta-manāḥ pārtha yogaṁ yuñjan mad-āśrayaḥ (BG 7.1). The āsakti, attachment, it has to be done according to the system, ādau śraddhā. First thing is śraddhā, little faith that, "Let us go to this Kṛṣṇa consciousness movement, and let us hear what they say." This is called śraddhā.