By performing congregational chanting of the Hare Krishna mantra, one can destroy the sinful condition of material existence, purify the unclean heart and awaken all varieties of devotional service.
Chaitanya Caritamrta on Antya Lila 20.13
Of the nine processes of devotional service, the most important is to always chant the holy name of the Lord. If one does so, avoiding the ten kinds of offenses, one very easily obtained the most valuable love of Godhead.
Chaitanya Caritamrta Antya Lila 4.71
If the surface of the globe is overflooded with the chanting of the Hare Krishna mantra, the people of the world will be very, very happy.
Purport on Srimad Bhagavatam on 4.24.10
Devotional service is called kirtana-yajna, and by practicing the sankirtana-yajna, one is very easily elevated to the planet where the Supreme Lord resides.
Purport on Srimad Bhagavatam 4.24.7
Simply by chanting the holy name of Lord Krishna, one can be freed from all undesirable habits. This is the means of awakening all good fortune and initiating the flow of waves of love for Krishna.
Chaitanya caritamrita Antya Lila 20.11
In Jagannatha Puri Chaitanya Mahaprabhu’s only occupation was holding Sankirtana at least four hours every day and distributing prasadam to the devotees.
As far as Sankirtana is concerned, that should be continued in all circumstances. Chanting of Hare Krishna, Sankirtana is our life and soul. Side by side, if possible, then you can attempt for the ISKCON restaurant and Krishna Prasadam distribution, but this I think is secondary.
Letter to Nathan baruch 1968.
Our first important business is to hold Sankirtana as many times as possible. The next important business is publication work.
Letter to Krishna Dasa – Los Angeles 28 July, 1969.
We are not much concerned about the temple because temple worship is not primary factor in this age. Primary factor is Sankirtana. But sometimes we want a center where people may gather and see, so a temple is required secondarily.
Letter to Mukunda – New Vrindaban 27 May, 1969.
Sukadeva Goswami says, this age is an ocean of faults, but there is one boon, in this age one gets the same result as was achieved in former ages through elaborate temple worship, costly sacrifices, or introspective meditation, simply by chanting the Holy Name of The Lord.
Letter to Achyutananda, 1975.