One's devotion and sincere desire to serve the Supreme Personality of Godhead are the only qualifications. Rūpa Gosvāmī has also said that the price for achieving God's favor is simply one's sincere eagerness to have it (laulyam ekaṁ mūlyam). In the Caitanya-bhāgavata it is said:
kholāvecā sevakera dekha bhāgya-sīmā
brahmā śiva kāṅde yāra dekhiyā mahimā
dhane jane pāṇḍitye kṛṣere nāhi pāi
kevala bhaktira vaśa caitanya-gosāñi
"Behold the great fortune of the devotee Kholāvecā. Lord Brahmā and Śiva shed tears upon seeing his greatness. One cannot attain Lord Kṛṣṇa by any amount of wealth, followers, or learning. Śrī Caitanya Mahāprabhu is controlled only by pure devotion. "
(Srimad Bhagavatam----5:19:7----purport).

The post of Lord Brahmā is meant for very highly elevated, spiritually advanced living beings. When such living beings are unavailable, Lord Viṣṇu, the Supreme Personality of Godhead, expands Himself as Lord Brahmā. This takes place very rarely. Consequently there are two kinds of Brahmās. Sometimes Brahmā is an ordinary living entity, and at other times Brahmā is the Supreme Personality of Godhead. The Brahmā spoken of here is an ordinary living being. Whether Brahmā is the Supreme Personality of Godhead or an ordinary living being, he is known as Vairāja Brahmā and Hiraṇyagarbha Brahmā. Therefore the sun-god is also accepted as Vairāja Brahmā.
(Srimad Bhagavatam----5:20:44----purport).

Of all sinful activities, an offense to a pure devotee, or Vaiṣṇava, is the most severe. An offense at the lotus feet of a Vaiṣṇava is so disastrous that Śrī Caitanya Mahāprabhu has compared it to a mad elephant that enters a garden and causes great havoc by uprooting many plants and trees. If one is an offender at the lotus feet of a brāhmaṇa or Vaiṣṇava, his offenses uproot all his auspicious activities. One should therefore very carefully guard against committing vaiṣṇava-aparādha, or offenses at the lotus feet of a Vaiṣṇava. Here the Lord clearly says that although Hiraṇyakaśipu had received benedictions from Lord Brahmā, these benedictions would be null and void as soon as he committed an offense at the lotus feet of Prahlāda Mahārāja, his own son.
(Srimad Bhagavatam----7:4:28----purport).

Hiraṇyakaśipu had received from Lord Brahmā the benediction that he would not die on the land or in the sky. Therefore, to keep the promise of Lord Brahmā intact, Nṛsiṁhadeva placed Hiraṇyakaśipu's body on His lap, which was neither land nor sky. Hiraṇyakaśipu had received the benediction that he would not die either during the day or at night. Therefore, to keep this promise of Brahmā, the Lord killed Hiraṇyakaśipu in the evening, which is the end of day and the beginning of night but is neither day nor night. Hiraṇyakaśipu had taken a benediction from Lord Brahmā that he would not die from any weapon or be killed by any person, dead or alive. Therefore, just to keep the word of Lord Brahmā, Lord Nṛsiṁhadeva pierced Hiraṇyakaśipu's body with His nails, which were not weapons and were neither living nor dead. Indeed, the nails can be called dead, but at the same time they can be said to be alive. To keep intact all of Lord Brahmā's benedictions, Lord Nṛsiṁhadeva paradoxically but very easily killed the great demon Hiraṇyakaśipu.
(Srimad Bhagavatam----7:4:29----purport).

Śrīla Narottama dāsa Ṭhākura has sung in his prema-bhakti-candrikā, 'krodha' bhakta-dveṣi jane: anger should be used to punish a demon who is envious of devotees. Kāma, krodha, lobha, moha, mada and mātsarya—lust, anger, greed, illusion, pride and envy—all have their proper use for the Supreme Personality of Godhead and His devotee. A devotee of the Lord cannot tolerate blasphemy of the Lord or His other devotees, and the Lord also cannot tolerate blasphemy of a devotee. Thus Lord Nṛsiṁhadeva was so very angry that the great demigods like LordBrahmā and Lord Śiva and even the goddess of fortune, who is the Lord's constant companion, could not pacify Him, even after offering prayers of glorification and praise.
(Srimad Bhagavatam----7:9:1----purport).

It appears that the words of the Supreme Personality of Godhead can be heard in trance by competent persons. Modern science gives us telephones, by which one can hear sound vibrations from a distant place. Similarly, although other persons cannot hear the words of Lord Viṣṇu, Lord Brahmā is able to hear the Lord's words within himself. This is confirmed in the beginning of Śrīmad-Bhāgavatam (1.1.1): tene brahma hṛdā ya ādi-kavaye. Ādi-kavi is Lord Brahmā. In the beginning of the creation, Lord Brahmā received the instructions of Vedic knowledge from Lord Viṣṇu through the medium of the heart (hṛdā). The same principle is confirmed herewith. While Brahmā was in trance, he was able to hear the words of Kṣīrodakaśāyī Viṣṇu, and he carried the Lord's message to the demigods. Similarly, in the beginning, Brahmā first received the Vedic knowledge from the Supreme Personality of Godhead through the core of the heart. In both instances the same process was used in transmitting the message to Lord Brahmā. In other words, although Lord Viṣṇu was invisible even to Lord Brahmā, Lord Brahmā could hear Lord Viṣṇu's words through the heart. The Supreme Personality of Godhead is invisible even to Lord Brahmā, yet He descends on this earth and becomes visible to people in general.
(Srimad Bhagavatam----10:1:21----purport).

Transcendental knowledge has to be accepted by the descending process of disciplic succession as Brahmā presents the knowledge of Kṛṣṇa in the Brahma-saṁhitā.Brahma-saṁhitā is vijñāna as realized by Brahmā's transcendental experience, and in that way he presented the form and the pastimes of Kṛṣṇa in the transcendental abode. Ajñāna-bhidā means "that which can match all kinds of speculation." In ignorance, people are imagining the form of the Lord; sometimes He has no form and sometimes He has form, according to their different imaginations. But the presentation of Kṛṣṇa in the Brahma-saṁhitā is vijñāna—scientific, experienced knowledge given by Lord Brahmā and accepted by Lord Caitanya. There is no doubt about it. Śrī Kṛṣṇa's form, Śrī Kṛṣṇa's flute, Kṛṣṇa's color—everything is reality. Here it is said that this vijñānam is always defeating all kinds of speculative knowledge. "Therefore," the demigods prayed, "without Your appearing as Kṛṣṇa, as You are, neither ajñāna-bhidā (the nescience of speculative knowledge) nor vijñānam would be realized. Ajñāna-bhidāpamārjanam—by Your appearance the speculative knowledge of ignorance will be vanquished, and the real, experienced knowledge of authorities like Lord Brahmā will be established.
(Srimad Bhagavatam----10:2:35----purport).

This chapter describes Lord Brahmā's attempt to take away the calves and cowherd boys, and it also describes the bewilderment of Lord Brahmā and finally the clearance of his illusion.
Although the incident concerning Aghāsura had been performed one year before, when the cowherd boys were five years old, when they were six years old they said, "It happened today." What happened was this. After killing Aghāsura, Kṛṣṇa, along with His associates the cowherd boys, went for a picnic within the forest. The calves, being allured by green grasses, gradually went far away, and therefore Kṛṣṇa's associates became a little agitated and wanted to bring back the calves. Kṛṣṇa, however, encouraged the boys by saying, "You take your tiffin without being agitated. I shall go find the calves." And thus the Lord departed. Then, just to examine the potency of Kṛṣṇa, Lord Brahmā took away all the calves and cowherd boys and kept them in a secluded place.
(Srimad Bhagavatam----10:13--summary).

When Kṛṣṇa was unable to find the calves and boys, He could understand that this was a trick performed by Brahmā. Then the Supreme Personality of Godhead, the cause of all causes, in order to please Lord Brahmā, as well as His own associates and their mothers, expanded Himself to become the calves and boys, exactly as they were before. In this way, He discovered another pastime. A special feature of this pastime was that the mothers of the cowherd boys thus became more attached to their respective sons, and the cows became more attached to their calves. After nearly a year, Baladeva observed that all the cowherd boys and calves were expansions of Kṛṣṇa. Thus He inquired from Kṛṣṇa and was informed of what had happened.
(Srimad Bhagavatam----10:13--summary).

When one full year had passed, Brahmā returned and saw that Kṛṣṇa was still engaged as usual with His friends and the calves and cows. Then Kṛṣṇa exhibited all the calves and cowherd boys as four-armed forms of Nārāyaṇa. Brahmā could then understand Kṛṣṇa's potency, and he was astonished by the pastimes of Kṛṣṇa, his worshipable Lord. Kṛṣṇa, however, bestowed His causeless mercy upon Brahmā and released him from illusion. Thus Brahmā began to offer prayers to glorify the Supreme Personality of Godhead.
(Srimad Bhagavatam----10:13--summary).

When Aghāsura was being killed by Kṛṣṇa, who was accompanied by His associates, Brahmā was astonished, but when he saw that Kṛṣṇa was very much enjoying His pastimes of lunch, he was even more astonished and wanted to test whether Kṛṣṇa was actually there. Thus he became entangled in Kṛṣṇa's māyā. After all, Brahmā was born materially. As mentioned here, ambhojanma janiḥ: he was born of ambhoja, a lotus flower. It does not matter that he was born of a lotus and not of any man, animal or material father. A lotus is also material, and anyone born through the material energy must be subject to the four material deficiencies: bhrama (the tendency to commit mistakes), pramāda (the tendency to be illusioned), vipralipsā (the tendency to cheat) and karaṇāpāṭava (imperfect senses). Thus Brahmā also became entangled.
Brahmā, with his māyā, wanted to test whether Kṛṣṇa was actually present. These cowherd boys were but expansions of Kṛṣṇa's personal self (ānanda-cinmaya-rasa-pratibhāvitābhiḥ (Bs. 5.37)). Later Kṛṣṇa would show Brahmā how He expands Himself into everything as His personal pleasure, ānanda-cinmaya-rasa. Hlādinī śaktir asmāt: Kṛṣṇa has a transcendental potency called hlādinī śakti. He does not enjoy anything that is a product of the material energy. Brahmā, therefore, would see Lord Kṛṣṇa expand His energy.
Brahmā wanted to take away Kṛṣṇa's associates, but instead he took away some other boys and calves. Rāvaṇa wanted to take away Sītā, but that was impossible, and instead he took away a māyā Sītā. Similarly, Brahmā took away māyārbhakāḥ: boys manifested by Kṛṣṇa's māyā. Brahmā could show some extraordinary opulence to the māyārbhakāḥ; but he could not show any extraordinary potency to Kṛṣṇa's associates. That he would see in the very near future. Māyārbhakasya īśituḥ. This bewilderment, this māyā, was caused by the supreme controller, prabhavataḥ—the all-potent Supreme person, Kṛṣṇa—and we shall see the result. Anyone materially born is subject to bewilderment. This pastime is therefore called brahma-vimohana-līlā, the pastime of bewildering Brahmā. Mohitaṁ nābhijānāti mām ebhyaḥ param avyayam (B.G.7:13). Materially born persons cannot fully understand Kṛṣṇa. Even the demigods cannot understand Him (muhyanti yat sūrayaḥ). Tene brahmā hṛdā ya ādi-kavaye (S.B.1:1:1). Everyone, from Brahmā down to the small insect, must take lessons from Kṛṣṇa.
(Srimad Bhagavatam----10:13:15----purport).

Kṛṣṇa could immediately understand that Brahmā had taken away both the calves and the boys, but as an innocent child He searched here and there so that Brahmā could not understand Kṛṣṇa's māyā. This was all a dramatic performance. A player knows everything, but still he plays on the stage in such a way that others do not understand him.
(Srimad Bhagavatam----10:13:16----purport).

Although Kṛṣṇa is viśva-vit, the knower of everything happening in the entire cosmic manifestation, as an innocent child He showed ignorance of Brahmā's actions, although He could immediately understand that these were the doings of Brahmā. This pastime is called brahma-vimohana, the bewilderment of Brahmā. Brahmā was already bewildered by Kṛṣṇa's activities as an innocent child, and now he would be further bewildered.
(Srimad Bhagavatam----10:13:17----purport).

Although Brahmā was already entangled in bewilderment, he wanted to show his power to the cowherd boys; but after he took away the boys and their calves and returned to his abode, Kṛṣṇa created further astonishment for Brahmā, and for the mothers of the boys, by establishing the lunch pastimes in the forest again and replacing all the calves and boys, just as they had appeared before. According to the Vedas, ekaṁ bahu syām: the Personality of Godhead can become many, many millions upon millions of calves and cowherd boys, as He did to bewilder Brahmā more and more.
(Srimad Bhagavatam----10:13:18----purport).

Kṛṣṇa usually stayed in the forest and pasturing ground, taking care of the calves and cows with His associates the cowherd boys. Now that the original group had been taken away by Brahmā, Kṛṣṇa Himself assumed the forms of every member of the group, without anyone's knowledge, even the knowledge of Baladeva, and continued the usual program.
(Srimad Bhagavatam----10:13:20----purport).

Inquiring from Kṛṣṇa about the actual situation, Lord Balarāma said, "My dear Kṛṣṇa, in the beginning I thought that all these cows, calves and cowherd boys were either great sages and saintly persons or demigods, but at the present it appears that they are actually Your expansions. They are all You; You Yourself are playing as the calves and cows and boys. What is the mystery of this situation? Where have those other calves and cows and boys gone? And why are You expanding Yourself as the cows, calves and boys? Will You kindly tell Me what is the cause?" At the request of Balarāma, Kṛṣṇa briefly explained the whole situation: how the calves and boys were stolen by Brahmā and how He was concealing the incident by expanding Himself so that people would not know that the original cows, calves and boys were missing.
(Srimad Bhagavatam----10:13:39----purport).

Lord Brahmā had gone away for only a moment of his time, but when he returned, a year of human time had passed. On different planets, the calculation of time is different. To give an example, a man-made satellite may orbit the earth in an hour and twenty-five minutes and thus complete one full day, although a day ordinarily takes twenty-four hours for those living on earth. Therefore, what was but a moment for Brahmā was one year on earth. Kṛṣṇa continued to expand Himself in so many forms for one year, but by the arrangement of yogamāyā no one could understand this but Balarāma.
After one moment of Brahmā's calculation, Brahmā came back to see the fun caused by his stealing the boys and calves. But he was also afraid that he was playing with fire. Kṛṣṇa was his master, and he had played mischief for fun by taking away Kṛṣṇa's calves and boys. He was really anxious, so he did not stay away very long; he came back after a moment (of his calculation). When Brahmā returned, he saw that all the boys, calves and cows were playing with Kṛṣṇa in the same way as when he had come upon them; by Kṛṣṇa's display of yogamāyā, the same pastimes were going on without any change.
(Srimad Bhagavatam----10:13:40----purport).

On the day when Lord Brahmā had first come, Baladeva could not go with Kṛṣṇa and the cowherd boys, for it was His birthday, and His mother had kept Him back for the proper ceremonial bath, called śāntika-snāna. Therefore Lord Baladeva was not taken by Brahmā at that time. Now, one year later, Brahmā returned, and because he returned on exactly the same day, Baladeva was again kept at home for His birthday. Therefore, although this verse mentions that Brahmā saw Kṛṣṇa and all the cowherd boys, Baladeva is not mentioned. It was five or six days earlier that Baladeva had inquired from Kṛṣṇa about the extraordinary affection of the cows and cowherd men, but now, when Brahmā returned, Brahmāsaw all the calves and cowherd boys playing with Kṛṣṇa as expansions of Kṛṣṇa, but he did not see Baladeva. As in the previous year, Lord Baladeva did not go to the woods on the day Lord Brahmā appeared there.
(Srimad Bhagavatam----10:13:40----purport).

For one year Lord Brahmā kept the calves and boys lying down in a cave by his mystic power. Therefore when Brahmā saw Lord Kṛṣṇa still playing with all the cows and calves, he began trying to reason about what was happening. "What is this?" he thought. "Maybe I took those calves and cowherd boys away but now they have been taken from that cave. Is this what has happened? Has Kṛṣṇa brought them back here?" Then, however, Lord Brahmā saw that the calves and boys he had taken were still in the same mystic māyā into which he had put them.
(Srimad Bhagavatam----10:13:41----purport).

Although appearing like calves, cows and cowherd boys, these were all Viṣṇu. Actually they were viṣṇu-tattva, not jīva-tattva. Brahmā was surprised. "The original cowherd boys and cows," he thought, "are still where I put them last year. So who is it that is now keeping company with Kṛṣṇa exactly as before? Where have they come from?" Brahmā was surprised that his mystic power had been neglected. Without touching the original cows and cowherd boys kept by Brahmā, Kṛṣṇa had created another assembly of calves and boys, who were all expansions of viṣṇu-tattva. Thus Brahmā's mystic power was superseded.
(Srimad Bhagavatam----10:13:42----purport).

Brahmā was puzzled. "The original boys and calves are still sleeping as I have kept them," he thought, "but another set is here playing with Kṛṣṇa. How has this happened?" Brahmā could not grasp what was happening. Which boys were real, and which were not real? Brahmā was unable to come to any definite conclusion. He pondered the matter for a long while. "How can there be two sets of calves and boys at the same time? Have the boys and calves here been created by Kṛṣṇa, or has Kṛṣṇa created the ones lying asleep? Or are both merely creations of Kṛṣṇa?" Brahmā thought about the subject in many different ways. "After I go to the cave and see that the boys and calves are still there, does Kṛṣṇa go take them away and put them here so that I come here and see them, and does Kṛṣṇa then take them from here and put them there?" Brahmā could not figure out how there could be two sets of calves and cowherd boys exactly alike. Although thinking and thinking, he could not understand at all.
(Srimad Bhagavatam----10:13:43----purport).

Brahmā wanted to bewilder Kṛṣṇa, who bewilders the entire universe. The whole universe is under Kṛṣṇa's mystic power (mama māyā duratyayā (B.G.7:14), but Brahmā wanted to mystify Him. The result was that Brahmā himself was mystified, just as one who wants to kill another may himself be killed. In other words, Brahmā was defeated by his own attempt. In a similar position are the scientists and philosophers who want to overcome the mystic power of Kṛṣṇa. They challenge Kṛṣṇa, saying, "What is God? We can do this, and we can do that." But the more they challenge Kṛṣṇa in this way, the more they are implicated in suffering. The lesson here is that we should not try to overcome Kṛṣṇa. Rather, instead of endeavoring to surpass Him, we should surrender to Him (sarva-dharmān parityajya mām ekaṁ śaraṇaṁ vraja (B.G.18:66).
Instead of defeating Kṛṣṇa, Brahmā himself was defeated, for he could not understand what Kṛṣṇa was doing. Since Brahmā, the chief person within this universe, was so bewildered, what is to be said of so-called scientists and philosophers?
(Srimad Bhagavatam----10:13:44----purport).

The word viṣṇum is significant in this verse. Viṣṇu pervades the entire material world, whereas Brahmā merely occupies one subordinate post.
yasyaika-niśvasita-kālam athāvalambya
jīvanti loma-vila-jā jagadaṇḍa-nāthāḥ
(Bs. 5.48)
The word nāthāḥ, which refers to Lord Brahmā, is plural because there are innumerable universes and innumerable Brahmās. Brahmā is but a tiny force. This was exhibited in Dvārakā when Kṛṣṇa called for Brahmā. One day when Brahmā came to see Kṛṣṇa at Dvārakā, the doorman, at Lord Kṛṣṇa's request, asked, "Which Brahmā are you?" Later, when Brahmā inquired from Kṛṣṇa whether this meant that there was more than one Brahmā, Kṛṣṇa smiled and at once called for many Brahmās from many universes. The four-headed Brahmā of this universe then saw innumerable other Brahmās coming to see Kṛṣṇa and offer their respects. Some of them had ten heads, some had twenty, some had a hundred and some had a million heads. Upon seeing this wonderful exhibition, the four-headed Brahmā became nervous and began to think of himself as no more than a mosquito in the midst of many elephants. Therefore, what can Brahmā do to bewilder Kṛṣṇa?
(Srimad Bhagavatam----10:13:44----purport).

When one wants to supersede a superior power, one's own inferior power becomes ludicrous. Just as a glowworm in the daytime and snow at night have no value,Brahmā's mystic power became worthless in the presence of Kṛṣṇa, for greater mystic power condemns inferior mystic power. On a dark night, the darkness produced by snow has no meaning. The glowworm appears very important at night, but in the daytime its glow has no value; whatever little value it has is lost. Similarly, Brahmā became insignificant in the presence of Kṛṣṇa's mystic power. Kṛṣṇa's māyā was not diminished in value, but Brahmā's māyā was condemned. Therefore, one should not try to exhibit one's insignificant opulence before a greater power.
(Srimad Bhagavatam----10:13:45----purport).

Now Brahmā saw Kṛṣṇa, the Supreme Personality of Godhead, appearing as a cowherd boy in Vṛndāvana, not demonstrating His opulence but standing just like an innocent boy with some food in His hand, loitering with His cowherd boyfriends, calves and cows. Brahmā did not see Kṛṣṇa as catur-bhuja, the opulent Nārāyaṇa; rather, he simply saw an innocent boy. Nonetheless, he could understand that although Kṛṣṇa was not demonstrating His power, He was the same Supreme person. people generally do not appreciate someone unless he shows something wonderful, but here, although Kṛṣṇa did not manifest anything wonderful, Brahmā could understand that the same wonderful person was present like an ordinary child, although He was the master of the whole creation. Thus Brahmā prayed, govindam ādi-puruṣaṁ tam ahaṁ bhajāmi. "You are the original person, the cause of everything. I bow down to You." This was his realization. Tam ahaṁ bhajāmi. This is what is wanted. Vedeṣu durlabham: one cannot reach Kṛṣṇa merely by Vedic knowledge. Adurlabham ātma-bhaktau: but when one becomes a devotee, then one can realize Him. Brahmā, therefore, became a devotee. In the beginning he was proud of being Brahmā, the lord of the universe, but now he understood, "Here is the Lord of the universe. I am simply an insignificant agent. Govindam ādi-puruṣaṁ tam ahaṁ bhajāmi.
(Srimad Bhagavatam----10:13:61----purport).

Lord Brahmā bowed down like a stick, and because Lord Brahmā's complexion is golden, he appeared to be like a golden stick lying down before Lord Kṛṣṇa. When one falls down before a superior just like a stick, one's offering of obeisances is called daṇḍavat. Daṇḍa means "stick," and vat means "like." It is not that one should simply say, "daṇḍavat." Rather, one must fall down. Thus Brahmā fell down, touching his foreheads to the lotus feet of Kṛṣṇa, and his crying in ecstasy is to be regarded as an abhiṣeka bathing ceremony of Kṛṣṇa's lotus feet.
(Srimad Bhagavatam----10:13:62----purport).

He who appeared before Brahmā as a human child was in fact the Absolute Truth, Parabrahman (brahmeti paramātmeti bhagavān iti śabdyate (S.B.1:2:11). The Supreme Lord is narākṛti; that is, He resembles a human being. It is not that He is four-armed (catur-bāhu). Nārāyaṇa is catur-bāhu, but the Supreme Person resembles a human being. This is also confirmed in the Bible, where it is said that man was made in the image of God.
(Srimad Bhagavatam----10:13:62----purport).

Lord Brahmā saw that Kṛṣṇa, in His form as a cowherd boy, was Parabrahman, the root cause of everything, but was now appearing as a human child, loitering in Vṛndāvana with a morsel of food in His hand. Astonished, Lord Brahmā hastily got down from his swan carrier and let his body fall to the earth. Usually, the demigods never touch the ground, but Lord Brahmā, voluntarily giving up his prestige as a demigod, bowed down on the ground before Kṛṣṇa. Although Brahmā has one head in each direction, he voluntarily brought all his heads to the ground and touched Kṛṣṇa's feet with the tips of his four helmets. Although his intelligence works in every direction, he surrendered everything before the boy Kṛṣṇa.
(Srimad Bhagavatam----10:13:62----purport).