Dvija-bandhu means born of a brāhmin father but his actions are like something else. He's called dvija-bandhu. Or born of a kṣatriya father. Dvija means brāhmin, kṣatriya and vaiśya also—those who are born for the second time by initiation. First birth is by the father and the mother, and the second birth is by the spiritual master and Vedic knowledge. Vedic knowledge is the mother, and spiritual master is the father. So when one approaches a bona fide spiritual master, his second birth is there by advancement of spiritual knowledge, and that sacred thread is offered to him. Upanayana. Upa means "near," and nayana means "bringing."
So this sacred thread is the symbol that one has accepted a spiritual master and he knows Vedic knowledge. That is the symbol of sacred thread. Ācāryavān puruṣo veda (Chāndogya Upaniṣad 6.14.2). One who has accepted a ācārya, it is to be understood that he knows things as they are. That is the symbol of sacred thread.
So those who are not mumukṣavaḥ, they are to considered under the influence of ignorance and passion. They are called rajas-tamaḥ-prakṛtayaḥ. Those who are on the platform of brahminical understanding, brahminical qualities, controlling the senses, controlling the mind, tolerant, simplicity . . .
And Śrī Baladeva Vidyābhūṣaṇa has given about this ārjava, "simplicity," he says that a brāhmin even to a enemy will disclose all his secrets. Even to his enemy. Nobody discloses his secrets before enemy, but a brāhmin, if he, even he finds out a enemy, he will disclose all the secrets. He has no secret. brāhmin means open-minded, liberal. And the opposite word is kṛpaṇa, miser.
So anyone who is trying to utilize fully the advantage of this human form of life, being desire of . . . desirous of becoming liberated from these material clutches and acts accordingly, he's a brāhmin. Mumukṣavaḥ. Others, who are not brāhmins—those who are influenced by the material ignorance and passion, rajas-tamaḥ-prakṛtayaḥ—their business is how to get money, how to get beautiful woman and how to have many followers.
Caitanya Mahāprabhu denies this. Caitanya Mahāprabhu says, na dhanaṁ na janaṁ na sundarīṁ kavitāṁ vā jagadīśa kāmaye. (CC Antya 20.29, Śikṣāṣṭaka 4) Caitanya Mahāprabhu says: "My dear Lord, Jagadīśa, I don't want riches," dhanam; na janam, "neither good," I mean to say, "progeny or followers," na dhanaṁ na janaṁ na sundarīṁ kavitāṁ vā jagadīśa kāma . . . sundarīṁ kavitām, "very poetic, beautiful wife." Na dhanaṁ na janaṁ na sundarīṁ kavitāṁ vā jagadīśa kāmaye. "I don't want all these things."