Persons who are unknowledgeable falsely identify with gross material consciousness and are full of material designations. This body is a gift of the material nature, and one who is too much attached to the bodily consciousness is called manda, or a lazy person without understanding of spirit soul. Ignorant men think of the body as the self; they accept bodily connections with others as kinsmanship, the land in which the body is obtained is their object of worship, and they consider the formalities of religious rituals to be ends in themselves. Social work, nationalism and altruism are some of the activities for such materially designated persons. Under the spell of such designations, they are always busy in the material field; for them spiritual realization is a myth, and so they are not interested. Those who are enlightened in spiritual life, however, should not try to agitate such materially engrossed persons. Better to prosecute one's own spiritual activities silently. Such bewildered persons may be engaged in such primary moral principles of life as nonviolence and similar materially benevolent work.
(Bhagavad-Gita------3:29-------purport).

As stated in the Brahma-saṁhitā, not only does the Supreme Soul enter each and every universe, but He enters even the atoms. The Supreme Soul is present everywhere in the dormant stage, and when one can see the presence of the Supreme Soul everywhere, one is liberated from material designations.
The word sarva-bhūteṣu is to be understood as follows. There are four different divisions of species-living entities which sprout from the earth, living entities born of fermentation or germination, living entities which come from eggs and living entities which come from the embryo. These four divisions of living entities are expanded in 8,400,000 species of life. A person who is freed from material designations can see the same quality of spirit present everywhere or in every manifested living entity.

(Srimad Bhagavatam------3:28:42--------purport).

Material designations create differentiation in terms of caste, color, creed, nationality, etc. Different gotras, or family designations, are distinctions in terms of the material body, but when one comes to Kṛṣṇa consciousness he immediately becomes one of the Acyuta-gotra, or descendants of the Supreme Personality of Godhead, and thus becomes transcendental to all considerations of caste, creed, color and nationality.

(Srimad Bhagavatam------4:21:12--------purport).

The mind is the cause of both material bondage and liberation. The impure mind thinks, "I am this body." The pure mind knows that he is not the material body; therefore the mind is considered to be the root of all material designations. Until the living entity is aloof from the association and contaminations of this material world, the mind will be absorbed in such material things as birth, death, disease, illusion, attachment, greed and enmity. In this way the living entity is conditioned, and he suffers material miseries.

(Srimad Bhagavatam------5:11:16--------purport).

The Nārada-pañcarātra also says:
sarvopādhi-vinirmuktaṁ
tat-paratvena nirmalam
hṛṣīkeṇa hṛṣīkeśa-
sevanaṁ bhaktir ucyate
(CC.2:19:170).
"One should be free from all material designations and cleansed of all material contamination. He should be restored to his pure identity, in which he engages his senses in the service of the proprietor of the senses. That is called devotional service." This is also called bhāgavata-dharma. Without material aspirations, one should simply serve Kṛṣṇa, as advised in Bhagavad-gītā, Nārada-pañcarātra and Śrīmad-Bhāgavatam.

(Srimad Bhagavatam------6:16:40--------purport).

The brāhmaṇas, the members of the most elevated varṇa, are teachers, but a person in a lower family, such as a family of kṣatriyas, vaiśyas or even śūdras, may be accepted as a teacher if he has knowledge. Śrī Caitanya Mahāprabhu approved of this when He expressed this opinion before Rāmānanda Rāya (CC.2:8:128):
kibā vipra, kibā nyāsī, śūdra kene naya
yei kṛṣṇa-tattva-vettā, sei 'guru' haya
It does not matter whether one is a brāhmaṇa, śūdra, gṛhastha or sannyāsī. These are all material designations. A spiritually advanced person has nothing to do with such designations. Therefore, if one is advanced in the science of Kṛṣṇa consciousness, regardless of his position in human society, he may become a spiritual master.

(Srimad Bhagavatam------6:7:33--------purport).