Whatever part of this world a person belongs to, if he follows the instructions of the Supreme Lord in the Bhagavad-gītā, then he attains the transcendental platform and can become even more elevated than a brāhmaṇa. As Lord Kṛṣṇa says in the Gītā (4.24),
A person who is fully absorbed in Kṛṣṇa consciousness is sure to attain the spiritual kingdom because of his full contribution to spiritual activities, in which the consummation is absolute and that which is offered is of the same spiritual nature.
This verse explains how one can attain spiritual knowledge by performing activities that please the Supreme Lord.
Śrīpāda Śaṅkarācārya propounded the impersonal theory, citing phrases like sarvaṁ khalv idaṁ brahma: "By nature everything is Brahman, spirit." Śaṅkarācārya's theory has caused great confusion about established scriptural conclusions, but this phrase clearly supports the the Gītā verse quoted above.
At this point it is urgent that we discuss how one can perform devotional service for the Supreme Lord's pleasure. In this regard it is also noteworthy how saintly leaders like King Janaka executed karma-yoga, or devotional service, by performing sacrifice. The aim of all sacrifices should be to please the Supreme Lord, Viṣṇu or Kṛṣṇa. Contact with matter is unavoidable in our present conditioned state, because while performing activities to sustain the body and to accomplish other purposes, we become intimate with material nature. But if we can spiritualize these activities by performing every one of them as a service to Brahman, the Supreme Absolute Truth, then these activities become yajña, or sacrifice. When the Vedic phrase sarvaṁ khalv idaṁ brahma is interpreted in this way, it is acceptable. In other words, when one invokes the spiritual or transcendental or absolute in everything, then matter loses its mundaneness, and then only can one realize the perfect meaning of the phrase sarvaṁ khalv idaṁ brahma. The Vaiṣṇavas say that anything connected with the Lord in devotional service is transcendental. In other words, it is nondifferent from the Supreme Lord Himself, Mādhava. Just as iron in long and constant touch with fire loses the characteristics of iron and becomes fiery, so everything offered in sacrifice to the Absolute, or the Transcendence, becomes absolute, or transcendental.
In the Bhagavad-gītā (14.27) Lord Kṛṣṇa says, "And I am the basis of the impersonal Brahman, which is the constitutional position of ultimate happiness." This verse unequivocally declares that Brahman is Lord Kṛṣṇa's bodily effulgence. Since Lord Kṛṣṇa is the source of Brahman, devotional service to Lord Kṛṣṇa establishes the true meaning of sarvaṁ khalv idaṁ brahma. A sacrifice is properly performed only when all the sacrificial ingredients—the offerings, the fire, the ghee, and so on—become spiritualized, or reach the stage of Brahman, by their contact with Lord Kṛṣṇa. And since the performance of sacrifice culminates in the manifestation of real love for Lord Viṣṇu, loving devotional service to Lord Viṣṇu is the very best form of sacrifice. Such a stage can be also described as total absorption in Brahman.