If Sankirtana is the method, for Kali Yuga, Japa, the method for Krita yuga, why is so much importance given to Japa and not Sankirtana?
Srimad Bhagavatam 12.3.52
krte yad dhyayato visnum
tretayam yajato makhaih
kalau tad dhari-kirtanat
krte -- in the Satya-yuga; yat -- which; dhyayatah -- from meditation; visnum -- on Lord Visnu; tretayam -- in the Treta-yuga; yajatah -- from worshiping; makhaih -- by performing sacrifices; dvapare -- in the age of Dvapara; paricaryayam -- by worshiping the lotus feet of Krsna; kalau -- in the age of Kali; tat -- that same result (can be achieved); hari-kirtanat -- simply by chanting the Hare Krsna maha-mantra.
Whatever result was obtained in Satya-yuga by meditating on Visnu, in Treta-yuga by performing sacrifices, and in Dvapara-yuga by serving the Lord's lotus feet can be obtained in Kali-yuga simply by chanting the Hare Krsna maha-mantra.
A similar verse is found in the Visnu Purana (6.2.17), and also in the Padma Purana (Uttara-khanda 72.25) and the Brhan-naradiya Purana (38.97):
dhyayan krte yajan yajnais
tretayam dvapare 'rcayan
yad apnoti tad apnoti
kalau sankirtya kesavam
"Whatever is achieved by meditation in Satya-yuga, by the performance of sacrifice in Treta-yuga, and by the worship of Lord Krsna's lotus feet in Dvapara-yuga is obtained in the age of Kali simply by glorifying the name of Lord Kesava."
Srila Jiva Gosvami has further quoted from the Brahma-vaivarta Purana concerning the degraded condition of people in Kali-yuga:
atah kalau tapo-yoga-
sanga bhavanti na krtah
kusalair api dehibhih
"Thus in the age of Kali the practices of austerity, yoga meditation, Deity worship, sacrifice and so on, along with their various subsidiary functions, are not properly carried out, even by the most expert embodied souls.
Srila Jiva Gosvami has also cited the Caturmasya-mahatmya of the Skanda Purana concerning the necessity of chanting Hare Krsna in this age:
tatha caivottamam loke
kalau yuge visesena
"In this way the most perfect penance to be executed in this world is the chanting of the name of Lord Sri Hari. Especially in the age of Kali, one can satisfy the Supreme Lord Visnu by performing sankirtana.''
In conclusion, massive propaganda should be made all over the world to induce people to chant the Hare Krsna mantra, by which human society can be rescued from the dangerous ocean of the age of Kali.
When Haridas Takore was asked how do you preach a non believer without committing an offence/Namaparada?
Haridas Takore Said,
"This the way by which the whole world will be inundated
with the chanting of the holy name: with loud congregational
chanting, the holy name is to be propagated widely among the
masses. Those who are faithful will come forward and choose a
bona fide spiritual master, receiving instructions and initiation
in the name from him. By sincere chanting they will surely
obtain love of Godhead, Krsnaprema."