Unless one is a fully qualified brahmana, he cannot advance in the spiritual science. A real brahmana is never envious of Vaisnavas. If he is, he is considered an imperfect neophyte. Impersonalist brahmanas are always opposed to Vaisnava principles. They are envious of Vaisnavas because they do not know the goal of life. Na te viduh svartha-gatim hi visnum [SB 7.5.31]. However, when a brahmana becomes a Vaisnava, there is no duality. If a brahmana does not become a Vaisnava, he certainly falls down from the brahmana platform. This is confirmed in  Srimad-Bhagavatam (11.5.3): na bhajanty avajananti sthanad bhrastah patanty adhah.

We can actually see that in this Age of Kali many so-called brahmanas are envious of Vaisnavas. The Kali-contaminated brahmanas consider Deity worship to be imaginative: arcye visnau sila-dhir gurusu nara-matir vaisnave jati-buddhih. Such a contaminated brahmana may superficially imagine a form of the Lord, but actually he considers the Deity in the temple to be made of stone or wood. Similarly, such a contaminated brahmana considers the guru to be an ordinary human being, and he objects when a Vaisnava is created by the Krsna consciousness movement. Many so-called brahmanas attempt to fight us, saying, “How can you create a brahmana out of a European or American? A brahmana can be born only in a brahmana family.” They do not consider that this is never stated in any revealed scripture. Lord Krsna specifically states in the Bhagavad-gita (4.13), catur-varnyam maya srstam guna-karma-vibhagasah: “According to the three modes of material nature and the work associated with them, the four divisions of human society are created by Me.”

Thus a brahmana is not a result of the caste system. He becomes a brahmana only by qualification. Similarly, a Vaisnava does not belong to a particular caste; rather, his designation is determined by the rendering of devotional service.

From Srila Prabhupada’s purport to CC Madhya 15.277