A brahmana must act as a brahmana

[Bhakti Vikasa Swami]

You should not claim falsely. If you are actually brahmana, you must act as a
brahmana. If you are a ksatriya, you must act as a ksatriya.

Guna-karma-vibhagasah. Not that "I am a brahmana; now I have become something
else." Just like in Calcutta we have seen there are small slaughterhouses, and
they have posted one deity, Goddess Kali, and have got sacred thread, and the
signboard is: "This meat is sacri..., slaughtered by a brahmana; therefore it
is pure." "Therefore it is pure." And that is going on. Oh, the meat-eaters,
they take all this meat, and they think, "It is the prasada of Goddess Kali,
and it is slaughtered by a brahmana. There is no sin; it is all right." This is
going on.

No. Brahmana is not meant for becoming a slaughterer, a killer. No. Brahmana
should be truthful. Brahmana should be cleansed, no sinful life. Brahmana
should be controlling the senses, controlling the mind. Brahmana must be
well-educated, jnana, and he must apply the knowledge in practical life and
believe in the Vedic injunctions. These are the qualifications of brahmana.
Similarly, there are qualification of ksatriyas, vaisyas. We should follow
that.
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From Srila Prabhupada's lecture on Bhagavad-gita 2.2–6 – December 11, 1972,
Ahmedabad