According to the Vaiṣṇava regulative principles, one must be initiated as a brāhmaṇa. The Hari-bhakti-vilāsa (2.6) quotes the following injunction from the Viṣṇu-yāmala:
adīkṣitasya vāmorukṛtaṁ sarvaṁ nirarthakam
paśu-yonim avāpnotidīkṣā-virahito janaḥ
“‘Unless one is initiated by a bona fide spiritual master, all his devotional activities are useless. A person who is not properly initiated can descend again into the animal species.’”
Hari-bhakti-vilāsa (2.10) further quotes:
ato guruṁ praṇamyaivaṁsarva-svaṁ vinivedya ca
gṛhṇīyād vaiṣṇavaṁ mantraṁdīkṣā-pūrvaṁ vidhānataḥ
“‘It is the duty of every human being to surrender to a bona fide spiritual master. Giving him everything — body, mind and intelligence — one must take Vaiṣṇava initiation from him.’”
"One should not proudly think that one can understand the transcendental loving service of the Lord simply by reading books... One must accept a Vaisnava guru (adau gurv-asrayam), and then by questions and answers one should gradually learn what pure devotional service to Krsna is. That is called the parampara system."
(Cc. Antya-lila 7.53, purp.) — AC Bhaktivedanta Swami Prabhupada
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