There are daśa-vidha-saṁskāra, ten kinds of purificatory process. When one undergoes all these processes and at last comes to the spiritual master, who gives him sacred thread as recognition of his second birth, dvija . . . dvija means second birth. One birth by the father and mother, and the other birth is by the spiritual master and Vedic knowledge. That is called second birth. Saṁskārād bhaved dvijaḥ. At that time he is given chance to study and understand what is Veda. Veda-pāṭhād bhaved vipraḥ. By studying very nicely all the Vedas, one becomes vipra. Then, when he actually realizes what is Brahma and his relationship with Him, then he becomes a brāhmin.
And above that situation, when from Brahma understanding, impersonal Brahma understanding, he comes to the platform of understanding Viṣṇu, Lord Viṣṇu, the Supreme Personality of Godhead, he becomes a Vaiṣṇava. This is the process. That is the perfectional process.
Kṛṣṇa therefore says in the Bhagavad-gītā, janma karma me divyaṁ yo jānāti tattvataḥ: "Anyone who knows Me in truth," what happens to him? Tyaktvā dehaṁ punar janma naiti (BG 4.9): "Such person, after giving up this body, do not come back again in this material world to accept a material body." Then what happens to him? Mām eti: "He comes to Me, back to home, back to Godhead."