[Lord Caitanya to Sanätana Gosvämé]: "...In the Kali-yuga the occupational duty of the people is to chant congregationally the holy name of Kåñëa."
In Kali-yuga one worships Lord Kåñëa by chanting Hare Kåñëa, Hare Kåñëa, Kåñëa Kåñëa, Hare Hare/ Hare Räma, Hare Räma, Räma Räma, Hare Hare. (Çré Caitanya-caritämåta Madhya-lélä 20.339)

Çré Madhväcärya has brought our attention to this quotation from the Näräyaëa-saàhitä:

In this age of Kali, real religious propapada should induce people to chant the Hare Kåñëa mahä-mantra.... Çréla Bhaktisiddhänta Sarasvaté Öhäkura comments in this regard in his Anubhäñya, wherein he quotes a verse from Näräyaëa-saàhitä:

[Éçvara Puré to Lord Caitanya]: " 'In this age of Kali there is no other religious principle than the chanting of the holy name, which is the essence of all Vedic hymns. This is the purport of all scriptures.' "
(Çré Caitanya-caritämåta Ädi-lélä 7.74)

In great jubilation, Çré Caitanya Mahäprabhu said, "My clear Svarüpa Dämodara and Rämänanda Räya, know from Me that chanting of the holy names is the most feasible means of salvation in this age of Kali."
(Çré Caitanya-caritämåta Antya-lélä 20.8)

The religious practice for the age of Kali is to broadcast the glories of the holy name. Only for this purpose has the Lord, in a yellow color, descended as Lord Caitanya.
In this age of Kali the practical system of religion for everyone is the chanting of the name of Godhead. This was introduced in this age by Lord Caitanya. Bhakti-yoga actually begins with the chanting of the holy name, as confirmed by Madhväcärya in his commentary on the Muëòaka Upaniñad. He quotes this verse from the Näräyaëa-saàhitä:

dväparéyair janair viñëuù
païcarätraiç tu kevalaiù
kalau tu näma-mätreëa
püjyate bhagavän hariù

"In the Dväpara-yuga people should worship Lord Viñëu only by the regulative principles of the Närada-païcarätra and other such authorized books. In the age of Kali, however, people should simply chant the holy names of the Supreme Personality of Godhead." (Çré Caitanya-caritämåta Ädi-lélä 3.40)

In Çrémad-Bhägavatam it is repeatedly and clearly said that the essence of religion in the age of Kali is the chanting of the holy name of Kåñëa.(Çré Caitanya-caritämåta Ädi-lélä 3.50 )

Rather than inventing one's own religious process, one should accept the approved method of religion for this age hari-näma-saìkértana:

[Särvabhauma Bhaööäcärya to King Pratäparudra]: Särvabhauma Bhaööäcärya replied, "This sweet transcendental sound is a special creation of the Lord known as prema-saìkértana, congregational chanting in love of Godhead. In this age of Kali, Çré Caitanya Mahäprabhu has descended to preach the religion of Kåñëa consciousness. Therefore the chanting of the holy names of Lord Kåñëa is the religious principle for this age. Anyone who worships Lord Caitanya Mahäprabhu by congregational chanting should be understood to be very intelligent. One who does not do so must be considered a victim of this age and bereft of all intelligence."
Rascals propose that anyone can invent his own religious process, and this proposition is condemned herein. If one actually wants to become religious, he must take up the chanting of the Hare Kåñëa rnahä-mantra.... Dharma, or religion, cannot be manufactured by a human being. Religion is the law or code of the Lord.... Dharma refers to the science of bhakti-yoga, which begins by the novice's chanting the holy name of the Lord (tan-näma-grahaëädibhiù).
In this age of Kali it is recommended in Caitanya-caritämåta, kali-kale dharma-kåñëa-näma-saìkértana. In the age of Kali the chanting of the holy name of the Lord is the method of religion approved by all Vedic scriptures. (Çré Caitanya-caritämåta Madhya-lélä 11.97-99)

Apart from the holy name's importance as a means toward individual spiritual perfection, a reading of Vaiñëava literature reveals the holy name to possess the broadest historical and universal significance as well. Chanting of the holy name is in fact described as the universal and supreme religion in the current epoch, an epoch referred to in traditional Indian texts as Kali-yuga, "the age of Kali," the great Iron Age, an age of materialism, hypocrisy, and quarrel. Kali-yuga is the last of the four Great Ages, each progressively worse than its predecessor, four vast epochs that cycle perpetually. The age of Kali is the age wherein human society degrades from human to subhuman, in which the people of the world forget their souls, identify with their gross bodies, and become mad competitors for the world's stock of material goods and pleasures. As stated in Çrémad-Bhägavatam, the unfortunate inhabitants of the Kali age are "quarrelsome, lazy, misguided, unlucky, and, above all, always disturbed."
    Because such unfortunate persons have little or no inclination toward spiritual advancement, there is a compelling need for a simple method by which they can wake up from their deathly slumber and receive the opportunity for spiritual emancipation. That Great Dispensation is the holy name. Declares Kåñëadäsa Kaviräja Gosvämé, "In the age of Kali, Lord Kåñëa has descended in the form of the holy name." The holy name is the one true glory, the one saving grace of this condemned age, as Çukadeva Gosvämé tells King Parékñit: "Although Kali-yuga is full of faults, there is still one good quality about this age. It is that simply by chanting the holy name of Kåñëa one can become free from material bondage and be promoted to the transcendental kingdom."
    Various means of spiritual advancement practiced in the previous eras are rendered virtually ineffectual in Kali by the degradation of human beings, individually and collectively. The chanting of the holy name now supersedes all other forms of spiritual discipline: "Whatever result was obtained in Satya-yuga by meditating on Viñëu, in Tretä-yuga by performing sacrifices, and in Dväpara-yuga by serving the Lord's lotus feet can also be obtained in Kali-yuga simply by chanting the holy name of the Lord." (Çrémad-Bhägavatam 12.3.52) The primacy and exclusivity of the practice of the holy name is emphatically declared in this oft-cited verse from the Båhan-näradéya Puräëa: "In this age of Kali there is no alternative, there is no alternative, there is no alternative for spiritual progress but the holy name, the holy name, the holy name of the Lord." Thus the chanting of the holy name of the Lord is the yuga-dharma, the universal and supreme religion of the age, meant to unite all faiths in common, joyful glorification of the one Supreme Lord.
    Although the chanting of the holy name has played a role in India's religious history for millennia, it was specifically propagated and popularized as the yuga-dharma by the great Caitanya, whose effulgent presence and fervid ecstasies drew millions into näma-dharma, the Religion of the Name. As the great popularizer of the holy name, Çré Caitanya was regarded and worshiped as the Kali-yuga avatära, the prime avatära (incarnation) for the age of Kali. Further, He was worshiped as the greatest incarnation of the Lord because He liberally bestowed pure kåñëa-bhakti, ecstatic love of God, upon all persons. The mahä-mantra, the chant popularized by Çré Caitanya, is specifically mentioned in the Kalisantaraëa Upaniñad as the exclusive means for escaping the debilitating conditions of the Kali age: "Hare Kåñëa, Hare Kåñëa, Kåñëa Kåñëa, Hare Hare/ Hare Räma, Hare Räma, Räma Räma, Hare Hare—these sixteen names composed of thirty-two syllables are the only means to counteract the evil effects of Kali-yuga. In all the Vedas it is seen that to cross the ocean of nescience there is no alternative to the chanting of the holy name." Not only does the holy name bestow the highest benefits upon human beings both individually and collectively, but it purifies even lower species of life. Any living being fortunate enough to hear the divine, transcendental sound incarnation of the Lord receives immense spiritual benefit.
    Çré Caitanya did not intend the holy name to remain confined to India, but predicted that the holy name would reach "every town and village." Four centuries later, this missionary ideal, based upon a compelling vision of the universality of the holy name, gained momentum through the efforts of Çréla Bhaktivinoda Öhäkura, a great follower and ninth-generation disciplic representative of Çré Caitanya. Writing in his religious journal Sajjana-toñané in 1885, he declared prophetically,

Lord Caitanya did not advent Himself to liberate only a few men in India. Rather, His main objective was to emancipate all living entities of all countries throughout the entire universe and preach the Eternal Religion.... There is no doubt that this unquestionable order will come to pass.... Very soon the unparalleled path of hari-näma-saìkértana will be propagated all over the world.... Oh, for that day when the fortunate English, French, Russian, German, and American people will take up banners, mådaìgas, and karatälas and raise kértana through their streets and towns! When will that day come? ... That day will witness the holy transcendental ecstasy of the Vaiñëava dharma to be the only dharma, and all the sects and religions will flow like rivers into the ocean of Vaiñëava dharma. When will that day come?

The holy name of Kåñëa, for so long concealed within India, locked away from Western view, has now entered the mainstream of Western society. It has become, so to speak, a "household mantra," available to everyone. But although it is in open, public view, the holy name is not an ordinary commodity one can find and purchase in the market. It is a hidden treasure. One must develop the eyes to see it or, rather, the ears to hear it. If one simply approaches the holy name with reverence and allows the holy name to enter through his ears into his heart, and especially if he accepts the divine name as his very life and soul, he can enter the deepest, most profound, most sublime of all spiritual mysteries. (Sri Namamrita, Introduction. Srila A. C. Bhaktivedanta Swami Prabhupad.)

yuga-dharma pravartäimu näma-saìkértana
cäri bhäva-bhakti diyä näcämu bhuvana

SYNONYMS
yuga-dharma—the religion of the age; pravartäimu—I shall inaugurate; näma-saìkértana—chanting of the holy name; cäri—four; bhäva—of the moods; bhakti—devotion; diyä—giving; näcämu—I shall cause to dance; bhuvana—the world.

TRANSLATION
“I shall personally inaugurate the religion of the age—näma-saìkértana, the congregational chanting of the holy name. I shall make the world dance in ecstasy, realizing the four mellows of loving devotional service." (Sri Chaitanya Charitamritam Adi-lila 3:19.)

äpani karimu bhakta-bhäva aìgékäre
äpani äcari’ bhakti çikhäimu sabäre

SYNONYMS
äpani—personally; karimu—I shall make; bhakta-bhäva—the position of a devotee; aìgékäre—acceptance; äpani—personally; äcari’—practicing; bhakti—devotional service; çikhäimu—I shall teach; sabäre—to all.

TRANSLATION
“I shall accept the role of a devotee, and I shall teach devotional service by practicing it Myself."

PURPORT
When one associates with a pure devotee, he becomes so elevated that he does not aspire even for särñöi, särüpya, sämépya or sälokya, because he feels that such liberation is a kind of sense gratification. Pure devotees do not ask anything from the Lord for their personal benefit. Even if offered personal benefits, pure devotees do not accept them, because their only desire is to satisfy the Supreme Personality of Godhead by transcendental loving service. No one but the Lord Himself can teach this highest form of devotional service. Therefore, when the Lord took the place of the incarnation of Kali-yuga to spread the glories of chanting Hare Kåñëa—the system of worship recommended in this age—He also distributed the process of devotional service performed on the platform of transcendental spontaneous love. To teach the highest principles of spiritual life, the Lord Himself appeared as a devotee in the form of Lord Caitanya. (Srila A.C. Bhaktivedanta Swami Prabhupad. Sri Chaitanya Charitamritam Adi-lila 3:20., purport.)

äpane nä kaile dharma çikhäna nä yäya
ei ta’ siddhänta gétä-bhägavate gäya

SYNONYMS
äpane—personally; nä kaile—if not practiced; dharma—religion; çikhäna—the teaching; nä yäya—does not advance; ei—this; ta’—certainly; siddhänta—conclusion; gétä—in the Bhagavad-gétä; bhägavate—in Çrémad-Bhägavatam; gäya—they sing.

TRANSLATION
“Unless one practices devotional service himself, he cannot teach it to others. This conclusion is indeed confirmed throughout the Gétä and Bhägavatam." (Sri Chaitanya Charitamritam Adi-lila 3:21.)

yadä yadä hi dharmasya
glänir bhavati bhärata
abhyutthänam adharmasya
tadätmänaà såjämy aham

SYNONYMS
yadä yadä—whenever; hi—certainly; dharmasya—of religious principles; gläniù—decrease; bhavati—there is; bhärata—O descendant of Bharata; abhyutthänam—increase; adharmasya—of irreligion; tadä—then; ätmänam—Myself; såjämi—manifest; aham—I.

TRANSLATION
“‘Whenever and wherever there is a decline in religious practice, O descendant of Bharata, and a predominant rise of irreligion—at that time I descend Myself." (Sri Chaitanya Charitamritam Adi-lila 3:22.)

pariträëäya sädhünäà
vinäçäya ca duñkåtäm
dharma-saàsthäpanärthäya
sambhavämi yuge yuge

SYNONYMS
pariträëäya—for the deliverance; sädhünäm—of the devotees; vinäçäya—for the destruction; ca—and; duñkåtäm—of the miscreants; dharma—religious principles; saàsthäpana-arthäya—for the purpose of establishing; sambhavämi—I appear; yuge yuge—in every age.

TRANSLATION
“‘To deliver the pious and to annihilate the miscreants, as well as to reestablish the principles of religion, I Myself appear, millennium after millennium.’" (Sri Chaitanya Charitamritam Adi-lila 3:23.)

PURPORT
Texts 22 and 23 were spoken by Lord Kåñëa in the Bhagavad-gétä (4.7–8). Texts 24 and 25, which follow, are also from the Bhagavad-gétä (3.24, 3.21). (Srila A.C. Bhaktivedanta Swami Prabhupad. Sri Chaitanya Charitamritam Adi-lila 3:23., purport.)

utsédeyur ime lokä
na kuryäà karma ced aham
saìkarasya ca kartä syäm
upahanyäm imäù prajäù

SYNONYMS
utsédeyuù—would fall into ruin; ime—these; lokäù—worlds; na kuryäm—did not perform; karma—action; cet—if; aham—I; saìkarasya—of unwanted population; ca—and; kartä—the creator; syäm—would become; upahanyäm—would spoil; imäù—these; prajäù—living entities.

TRANSLATION
“‘If I did not show the proper principles of religion, all these worlds would fall into ruin. I would be the cause of unwanted population and would spoil all these living beings.’" (Sri Chaitanya Charitamritam Adi-lila 3:24.)

yad yad äcarati çreñöhas
tat tad evetaro janaù
sa yat pramäëaà kurute
lokas tad anuvartate

SYNONYMS
yat yat—however; äcarati—behaves; çreñöhaù—the best man; tat tat—that; eva—certainly; itaraù—the lesser; janaù—man; saù—he; yat—which; pramäëam—standard; kurute—shows; lokaù—the people; tat—that; anuvartate—follow.

TRANSLATION
“‘Whatever actions a great man performs, common people follow. And whatever standards he sets by exemplary acts, all the world pursues.’ " (Sri Chaitanya Charitamritam Adi-lila 3:25.)

Srimad Bhagavatam  1:1:10. purport says  The people in this age are very short-lived and slow in understanding spiritual life. Actually, human life is meant for understaëding spiritual values, but because everyone in this age is a çüdra, no one is interested. People have forgotten life's real purpose. The word manda means both slow and bad, and everyone in this age is either bad or slow or a combination of both. People are unfortunate and disturbed by so many things. According to Çrémad-Bhägavatam there will eventually be no rain and consequently a scarcity of food. The governments will also levy very heavy taxes. The characteristics of this age predicted by Çrémad-Bhägavatam are already being experienced to some degree. Since Kali-yuga is a very miserable age, Caitanya Mahäprabhu, who is Çré Kåñëa Himself, advises everyone simply to chant Hare Kåñëa.

"In this age of Kali there is no alternative, there is no alternative, there is no alternative for spiritual progress than the holy name, the holy name, the holy name of the Lord." (Båhan-näradéya Puräëa)

This process is not Caitanya Mahäprabhu's invention, but is advised by the çästras, the Puräëas. The process for this Kali-yuga is very simple. One need only chant the Hare Kåñëa mahä-mantra.(Teachings of Lord Kapila, the Son of Devahüti)

Although God has given us all facilities to live peacefully on this earth, cultivate Kåñëa consciousness, and finally to come to Him, in this age we're unfortunate. We are short-lived, and there are so many people without food, shelter, married life or defense from the onslaughts of nature. This is due to the influence of this age of Kali. Therefore Lord Caitanya Mahäprabhu, seeing the dreadful situation in this age, emphasized the absolute necessity for cultivating spiritual life. And how should we do it? Caitanya Mahäprabhu gives the formula:

"Just always chant Hare Kåñëa." Never mind whether you are in a factory or in hell, in a shack or in a skyscraper—it doesn't matter. Just go on chanting Hare Kåñëa, Hare Kåñëa, Kåñëa Kåñëa, Hare Hare/ Hare Räma, Hare Räma, Räma Räma, Hare Hare. There is no expense, there is no impediment, there is no caste, there is no creed, there is no color—anyone can do it. Just chant and hear. (On the Way to Kåñëa)

Everywhere in this age of iron everything is degraded, degraded in this sense: prayeëälpäyuñaù sabhya kaläv asmin yuge janäù [Srimad Bhagavatam  1.1.10]. In this age of Kali the duration of life is diminished, and men are not moved to understand self-realization, and if they are, they are invariably misled by so many deceitful leaders. The age is very corrupt. Therefore Caitanya Mahäprabhu's process of chanting Hare Kåñëa is the best and the simplest method.

"In this age of Kali there is no other religion than glorifying the Lord by utterance of His holy name, and that is the injunction of all the revealed scriptures. There is no other way, there is no other way, there is no other way."
 This verse appears in the Båhan-näradéya Puräëa. Harer näma harer näma harer nämaiva kevalam. Simply chant Hare Kåñëa. There is no other alternative. Kalau nästy eva nästy eva nästy eva gatir anyathä. In this age of Kali, there is no other alternative for self-realization. So we have to accept it.
There is another similar verse in the Çrémad-Bhägavatam. In the Twelfth Canto, Third Chapter (12.3.51), Parékñit Mahäräja was informed by Çukadeva Gosvämé of the faults of this age, and now all the symptoms of the age of Kali are apparent. In the conclusive portion, however, Çukadeva Gosvämé said, kaler doña-nidhe räjann asti hy eko mahän guëaù: "My dear king, this age, Kali, is full of faulty things, but there is one good opportunity." What is that? Kértanäd eva kåñëasya mukta-saìgaù paraà vrajet: "Simply by chanting this Hare Kåñëa mantra one can become liberated and go back to Godhead." (The Science of Self-Realization)

The lack of religious principles in Kali-yuga is more than compensated by the process of chanting the holy name:

It is said that this age of Kali is three-fourths devoid of religious principles. Hardly one-fourth of the principles of religion are still observed in this age. But by the mercy of Lord Kåñëa, this vacancy of Kali-yuga has not only been completely filled, but the religious process has been made so easy that simply by rendering transcendental loving service unto Lord Kåñëa by chanting His holy names, Hare Kåñëa, Hare Kåñëa, Kåñëa Kåñëa, Hare Hare/ Hare Räma, Hare Räma, Räma Räma, Hare Hare, one can achieve the highest result of religion, namely, being transferred to the highest planet within the spiritual world, Goloka Våndävana.
(Kåñëa, the Supreme Personality of Godhead)

 Chanting of the holy names of the Lord is the common platform for the universal religion of mankind in the Kali-yuga:

In this present age quarrels take place even over trifles, and therefore the çästras have recommended for this age a common platform for realization, namely chanting the holy names of the Lord. People can hold meetings to glorify the Lord in their respective languages and with melodious songs, and if such perfommances are executed in an offenseless manner, it is certain that the participants will gradually attain spiritual perfection without having to undergo more rigorous methods. At such meetings everyone, the learned and the foolish, the rich and the poor, the Hindus and the Muslims, the Englishmen and the Indians, and the caëòälas and the brähmaëas, can all hear the transcendental sounds and thus cleanse the dust of material association from the mirror of the heart. To confirm the Lord's mission, all the people of the world will accept the holy name of the Lord as the common platform for the universal religion of mankind. (Çrémad-Bhägavatam 1, Intro.)

In the age of logic, argument and disagreement, the chanting of Hare Kåñëa is the only means of self-realization:

In three out of the four millenniums (namely Satya-yuga, Tretä-yuga and Dväpara-yuga) people had the honor to be able to understand transcendence through the path of disciplic succession. However, in the present age, people have no interest in the disciplic succession. Instead, they have invented many paths of logic and argument. This individual attempt to understand the supreme transcendence (called the ascending process) is not approved by the Vedas. The Absolute Truth must descend from the absolute platform. He is not to be understood by the ascending process. The holy name of the Lord—Hare Kåñëa, Hare Kåñëa, Kåñëa Kåñëa, Hare Hare/ Hare Räma, Hare Räma, Räma Räma, Hare Hare—is a transcendental vibration because it comes from the transcendental platform, the supreme abode of Kåñëa. Because there is no difference between Kåñëa and His name, the holy name of Kåñëa is as pure, perfect and liberated as Kåñëa Himself. Academic scholars have no entrance by means of logic and other argument into the understanding of the transcendental nature of the holy name of God. The single path in understanding the transcendental nature of Hare Kåñëa, Hare Kåñëa, Kåñëa Kåñëa, Hare Hare/ Hare Räma, Hare Räma, Räma Räma, Hare Hare is the chanting of these names with faith and adherence. Such chanting will release one from designated conditions arising from the gross and subtle bodies.
    In this age of logic, argument and disagreement, the chanting of Hare Kåñëa is the only means for self-realization.(Teachings of Lord Caitanya)

The Hare Kåñëa mantra is especially suited to deliver us from the dangers of the Kali-yuga:

Only the dvijas (the brähmaëas) and the devas (the demigods) can be delivered from material existence by the instructions of the Supreme Personality of Godhead. Whatever is spoken by the Supreme Personality of Godhead is a mantra and is suitable for delivering the conditioned souls from mental speculation. The conditioned souls are engaged in a struggle for existence (manaù ñañöhänéndriyäëi prakåti-sthäni karñati [Bg. 15.7]). Deliverance from this struggle constitutes the highest benefit, but unless one gets a mantra from the Supreme Personality of Godhead, deliverance is impossible. The beginning mantra is the Gäyatré mantra. Therefore, after purification, when one is qualified to become a brähmaëa (dvija), he is offered the Gäyatré mantra. Simply by chanting the Gäyatré mantra, one can be delivered. This mantra, however, is suitable only for the brähmaëas and demigods. In Kali-yuga, we are all in a very difficult position, in which we need a suitable mantra that can deliver us from the dangers of this age. Therefore the Supreme Personality of Godhead, in His incarnation as Lord Caitanya, gives us the Hare Kåñëa mantra.... In His Çikñäñöaka, Lord Caitanya says, paraà vijayate çré-kåñëa-saìkértanam: "All glories to the chanting of çré-kåñëa-saìkértana!" The mahä-mantra—Hare Kåñëa, Hare Kåñëa, Kåñëa Kåñëa, Hare Hare/ Hare Räma, Hare Räma, Räma Räma, Hare Hare—is directly chanted by the Lord Himself, who gives us this mantra for deliverance.
    We cannot invent any means to be delivered from the dangers of material existence.... Sparks are beautiful as long as they are in the fire. Similarly, we have to remain in the association of the Supreme Personality of Godhead and always engage in devotional service, for then we shall always be brilliant and illuminating. As soon as we fall from the service of the Lord, our brilliance and illumination will immediately be extinguished, or at least stopped for some time. When we living entities, who are like sparks of the original fire, the Supreme Lord, fall into a material condition, we must take the mantra from the Supreme Personality of Godhead as it is offered by Çré Caitanya Mahäprabhu. By chanting this Hare Kåñëa mantra, we shall be delivered from all the difficulties of this material world. (Çrémad-Bhägavatam 8.6.15, Bhaktivedanta purort.)