In the Padma Purāṇa, the characteristics of the guru, the bona fide spiritual master, have been described:

mahā-bhāgavata-śreṣṭho brāhmaṇo vai gurur nṛṇām
sarveṣām eva lokānām asau pūjyo yathā hariḥ

mahā-kula-prasūto ’pi sarva-yajñeṣu dīkṣitaḥ
sahasra-śākhādhyāyī ca na guruḥ syād avaiṣṇavaḥ

The guru must be situated on the topmost platform of devotional service. There are three classes of devotees, and the guru must be accepted from the topmost class. The first-class devotee is the spiritual master for all kinds of people. It is said, gurur nṛṇām. The word nṛṇām means “of all human beings.” The guru is not limited to a particular group. It is stated in the Upadeśāmṛta of Rūpa Gosvāmī that a guru is a gosvāmī, a controller of the senses and the mind. Such a guru can accept disciples from all over the world. Pṛthivīṁ sa śiṣyāt. This is the test of the guru.

In India there are many so-called gurus, and they are limited to a certain district or a province. They do not even travel about India, yet they declare themselves to be jagad-guru, the guru of the whole world. Such cheating gurus should not be accepted. Anyone can see how the bona fide spiritual master accepts disciples from all over the world. The guru is a qualified brāhmaṇa; therefore he knows Brahman and Parabrahman. He thus devotes his life for the service of Parabrahman. The bona fide spiritual master who accepts disciples from all over the world is also worshiped all over the world because of his qualities. Lokānām asau pūjyo yathā hariḥ: the people of the world worship him just as they worship the Supreme Personality of Godhead. All these honors are offered to him because he strictly follows the brahminical principles and teaches these principles to his disciples. Such a person is called an ācārya because he knows the principles of devotional service, he behaves in that way himself, and he teaches his disciples to follow in his footsteps. Thus he is an ācārya or jagad-guru. Even though a person is born in a brahminical family and is very expert in performing sacrifices, he cannot be accepted as a guru if he is not a strict Vaiṣṇava. A guru is a brāhmaṇa by qualification, and he can turn others into brāhmaṇas according to the śāstric principles and brahminical qualifications. Brahmanism is not a question of heredity. In Śrīmad-Bhāgavatam (7.11.35) Śrī Nārada Muni tells Mahārāja Yudhiṣṭhira what a brāhmaṇa is. He states that if brahminical qualifications are observed in kṣatriyas, vaiśyas or even śūdras, one should accept them as brāhmaṇas. In this regard, Śrīla Śrīdhara Svāmī has commented: śamādibhir eva brāhmaṇādi-vyavahāro mukhyaḥ, na jāti-mātrādīty āha — yasyeti. yad yadi anyatra varṇāntare ’pi dṛśyeta, tad-varṇāntaraṁ tenaiva lakṣaṇa-nimittenaiva varṇena vinirdiśet, na tu jāti-nimittenety arthaḥ: “The most important criterion for deciding whether to deal with someone as a brāhmaṇa or as a member of another varṇa is the presence or absence of self-control and similar brahminical qualities. We should not judge primarily according to superficial characteristics like birth. This is stated in the verse beginning yasya [Bhāg. 7.11.35]. If the qualities of one varṇa are seen in someone born in another, he should be designated according to the varṇa of his qualities, not that of his birth.”

There is a similar statement made by Nīlakaṇṭha, a commentator on the Mahābhārata: śūdro ’pi śamādy-upeto brāhmaṇa eva brāhmaṇo ’pi kāmādy-upetaḥ śūdra eva. “Although one may be born in a śūdra family, if he is endowed with the brahminical qualities, beginning with śama [control of the mind], he is to be accepted as a brāhmaṇa. Although one may be born in a brāhmaṇa family, if he is endowed with the qualities beginning with kāma [lust], he is to be considered a śūdra.” No one should present himself as a brāhmaṇa simply on the basis of being born in a brahminical family. One must be qualified by the brahminical qualities mentioned in the śāstras, particularly the Bhagavad-gītā (18.42):

śamo damas tapaḥ śaucaṁ kṣāntir ārjavam eva ca
jñānaṁ vijñānam āstikyaṁ brahma-karma svabhāva-jam

“Peacefulness, self-control, austerity, purity, tolerance, honesty, knowledge, wisdom and religiousness — these are the natural qualities by which the brāhmaṇas work.”

Unless one is qualified with all these attributes, he cannot be accepted as a brāhmaṇa. It is not a question of simply taking birth in a brāhmaṇa family. In this regard, Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura remarks that Narottama dāsa Ṭhākura and Śyāmānanda Gosvāmī, although not born in brāhmaṇa families, are accepted as bona fide spiritual masters because they were brāhmaṇas by qualification. Personalities like Śrī Gaṅgā-nārāyaṇa, Rāmakṛṣṇa and many others, who were actually born in brāhmaṇa families, accepted Narottama dāsa Ṭhākura and Śyāmānanda Gosvāmī as their spiritual masters.

The mahā-bhāgavata is one who decorates his body with tilaka and whose name indicates him to be a servant of Kṛṣṇa by the word dāsa. He is also initiated by a bona fide spiritual master and is expert in worshiping the Deity, chanting mantras correctly, performing sacrifices, offering prayers to the Lord and performing saṅkīrtana. He knows how to serve the Supreme Personality of Godhead and how to respect a Vaiṣṇava. When one has attained the topmost position of mahā-bhāgavata, he is to be accepted as a guru and worshiped exactly like Hari, the Personality of Godhead. Only such a person is eligible to occupy the post of a guru. However, if one is highly qualified but is not a Vaiṣṇava, he cannot be accepted as a guru. One cannot be a brāhmaṇa unless one is a Vaiṣṇava. If one is a Vaiṣṇava, he is already a brāhmaṇa. If a guru is completely qualified as a Vaiṣṇava, he must be accepted as a brāhmaṇa even if he is not born in a brāhmaṇa family. The caste system method of distinguishing a brāhmaṇa by birth is not acceptable when applied to a bona fide spiritual master. A spiritual master is a qualified brāhmaṇa and ācārya. If one is not a qualified brāhmaṇa, he is not expert in studying the Vedic literatures. Nānā-śāstra-vicāraṇaika-nipuṇau. Every Vaiṣṇava is a spiritual master, and a spiritual master is automatically expert in brahminical behavior. He also understands the Vedic śāstras.

Similarly, a disciple’s qualifications must be observed by the spiritual master before he is accepted as a disciple. In our Kṛṣṇa consciousness movement, the requirement is that one must be prepared to give up the four pillars of sinful life — illicit sex, meat-eating, intoxication and gambling. In Western countries especially, we first observe whether a potential disciple is prepared to follow the regulative principles. Then he is given the name of a Vaiṣṇava servant and initiated to chant the Hare Kṛṣṇa mahā-mantra, at least sixteen rounds daily. In this way the disciple renders devotional service under the guidance of the spiritual master or his representative for at least six months to a year. He is then recommended for a second initiation, during which a sacred thread is offered and the disciple is accepted as a bona fide brāhmaṇa. Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura introduced the system of giving the sacred thread to a bona fide Vaiṣṇava, and we are following in his footsteps. The qualifications of a bona fide disciple are described in Śrīmad-Bhāgavatam (11.10.6) as follows:

amānya-matsaro dakṣo nirmamo dṛḍha-sauhṛdaḥ
asatvaro ’rtha-jijñāsur anasūyur amogha-vāk

The disciple must have the following qualifications. He must give up interest in the material bodily conception. He must give up material lust, anger, greed, illusion, madness and envy. He should be interested only in understanding the science of God, and he should be ready to consider all points in this matter. He should no longer think, “I am this body,” or, “This thing belongs to me.” One must love the spiritual master with unflinching faith, and one must be very steady and fixed. The bona fide disciple should be inquisitive to understand transcendental subject matter. He must not search out faults among good qualities, and he should no longer be interested in material topics. His only interest should be Kṛṣṇa, the Supreme Personality of Godhead.

As far as the mutual testing of the spiritual master and disciple is concerned, Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura explains that a bona fide disciple must be very inquisitive to understand the transcendental subject matter. As stated in Śrīmad-Bhāgavatam (11.3.21):

tasmād guruṁ prapadyeta jijñāsuḥ śreya uttamam

“One who is inquisitive to understand the highest goal and benefit of life must approach a bona fide spiritual master and surrender unto him.” A serious disciple must be alert when selecting a bona fide spiritual master. He must be sure that the spiritual master can deliver all the transcendental necessities. The spiritual master must observe how inquisitive the disciple is and how eager he is to understand the transcendental subject matter. The spiritual master should study the disciple’s inquisitiveness for no less than six months or a year. A spiritual master should not be very anxious to accept a disciple because of his material opulences. Sometimes a big businessman or landlord may approach a spiritual master for initiation. Those who are materially interested are called viṣayīs (karmīs), which indicates that they are very fond of sense gratification. Such viṣayīs sometimes approach a famous guru and ask to become a disciple just as a matter of fashion. Sometimes viṣayīs pose as disciples of a reputed spiritual master just to cover their activities and advertise themselves as advanced in spiritual knowledge. In other words, they want to attain material success. A spiritual master must be very careful in this regard. Such business is going on all over the world. The spiritual master does not accept a materially opulent disciple just to advertise the fact that he has such a big disciple. He knows that by associating with such viṣayī disciples, he may fall down. One who accepts a viṣayī disciple is not a bona fide spiritual master. Even if he is, his position may be damaged due to association with an unscrupulous viṣayī. If a so-called spiritual master accepts a disciple for his personal benefit or for material gain, the relationship between the spiritual master and the disciple turns into a material affair, and the spiritual master becomes like a smārta-guru. There are many caste gosvāmīs who professionally create some disciples who do not care for them or their instructions. Such spiritual masters are satisfied simply to get some material benefits from their disciples. Such a relationship is condemned by Śrīla Bhaktisiddhānta Sarasvatī Ṭhākura, who calls such spiritual masters and disciples a society of cheaters and cheated. They are also called bāulas or prākṛta-sahajiyās. Their aim is to make the connection between the spiritual master and the disciple into a very cheap thing. They are not serious in wanting to understand spiritual life.

The words sevya bhagavān in this verse of the Caitanya-caritāmṛta are important. Bhagavān indicates the Supreme Personality of Godhead, Lord Viṣṇu. Lord Viṣṇu alone is worshipable. There is no need to worship demigods. This is confirmed in the Bhagavad-gītā (7.20):

kāmais tais tair hṛta-jñānāḥ prapadyante ’nya-devatāḥ
taṁ taṁ niyamam āsthāya prakṛtyā niyatāḥ svayā

“Those whose intelligence has been stolen by material desires surrender unto demigods and follow the particular rules and regulations of worship according to their own natures.”

It is also stated in the Skanda Purāṇa:

vāsudevaṁ parityajya yo ’nya-devam upāsate
sva-mātaraṁ parityajya śva-pacīṁ vandate hi saḥ

“A person who worships the demigods and gives up Lord Vāsudeva is like a man who gives up the protection of his mother for the shelter of a witch.”

It is also stated by Lord Kṛṣṇa in the Bhagavad-gītā (9.23):

ye ’py anya-devatā-bhaktā yajante śraddhayānvitāḥ
te ’pi mām eva kaunteya yajanty avidhi-pūrvakam

“Those who are devotees of other gods and who worship them with faith actually worship only Me, O son of Kuntī, but they do so in a wrong way.”

Demigods are also living entities and parts and parcels of Kṛṣṇa. Therefore in one sense one worships Kṛṣṇa when one worships the demigods, but not in the proper way. There is a proper method to water a tree: one should water the root. But if one waters the leaves and branches instead, he is simply wasting his time. If one worships the demigods to the exclusion of Lord Viṣṇu, his rewards will only be material. As confirmed by Lord Kṛṣṇa in the Bhagavad-gītā (7.23):

anta-vat tu phalaṁ teṣāṁ tad bhavaty alpa-medhasām
devān deva-yajo yānti mad-bhaktā yānti mām api

“Men of small intelligence worship the demigods, and their fruits are limited and temporary. Those who worship the demigods go to the planets of the demigods, but My devotees ultimately reach My supreme planet.”

Demigod worship is meant for unintelligent men because the benefits derived from demigod worship are all material, temporary and retractable. It is also stated in the Padma Purāṇa:

yas tu nārāyaṇaṁ devaṁ brahma-rudrādi-daivataiḥ
samatvenaiva vīkṣeta sa pāṣaṇḍī bhaved dhruvam

“Whoever thinks Lord Viṣṇu and the demigods are on the same level is to be immediately considered a rogue as far as spiritual understanding is concerned.”

There are three modes of nature in the material world, but when one is situated spiritually, he is above the material modes, even though he lives in this material world. As Lord Kṛṣṇa states in the Bhagavad-gītā (14.26):

māṁ ca yo ’vyabhicāreṇa bhakti-yogena sevate
sa guṇān samatītyaitān brahma-bhūyāya kalpate

“One who engages in full devotional service, unfailing in all circumstances, at once transcends the modes of material nature and thus comes to the level of Brahman.” In material consciousness, however, even one who is situated in the mode of goodness is susceptible to pollution by the modes of passion and ignorance. When the mode of goodness is mixed with the mode of passion, one worships the sun-god, Vivasvān. When the mode of goodness is mixed with the mode of ignorance, one worships Gaṇapati, or Gaṇeśa. When the mode of passion is mixed with the mode of ignorance, one worships Durgā, or Kālī, the external potency. When one is simply in the mode of ignorance, one becomes a devotee of Lord Śiva because Lord Śiva is the predominating deity of the mode of ignorance within this material world. However, when one is completely free from the influence of all the modes of material nature, one becomes a pure Vaiṣṇava on the devotional platform. As Śrīla Rūpa Gosvāmī states in the Bhakti-rasāmṛta-sindhu:

anyābhilāṣitā-śūnyaṁ jñāna-karmādy-anāvṛtam
ānukūlyena kṛṣṇānu- śīlanaṁ bhaktir uttamā

“One should render transcendental loving service to the Supreme Lord Kṛṣṇa favorably and without desire for material profit or gain through fruitive activities or philosophical speculation. That is called pure devotional service.”

The position of viśuddha-sattva is the position of uncontaminated goodness. On that platform one can then understand, ārādhyo bhagavān vrajeśa-tanayas tad-dhāma vṛndāvanam: “The Supreme Personality of Godhead, the son of Nanda Mahārāja, is to be worshiped along with His transcendental abode, Vṛndāvana.”

The word sarva-mantra-vicāraṇa in the present verse of Śrī Caitanya-caritāmṛta means “considering all different types of mantras.” There are different kinds of mantras for different kinds of devotees. There is the mantra known as the dvādaśākṣara mantra, composed of twelve syllables, and there is the mantra composed of eighteen syllables. Similarly, there are the Nārasiṁha mantra, the Rāma mantra, the Gopāla mantra and so on. Each and every mantra has its own spiritual significance. The spiritual master has to select a mantra for his disciple according to the disciple’s ability to chant different mantras.