Prabhupada:
sādhu-saṅga sādhu-saṅga sarva-śāstre kaya
lava-mātra sādhu-saṅge sarva-siddhi haya
[Cc. Madhya 22.54]
Actually if one associates with a sādhu, with a pure devotee of Lord, then certainly it will be effective. Certainly. This Kṛṣṇa consciousness society is meant for giving opportunity to the people to make association with bhaktas. By association with bhakta, devotees, they'll become also bhakta. Saṅgāt sañjāyate kāmaḥ [Bg. 2.62]. If you associate with drunkards, then you gradually become a drunkard. But if you associate with devotees, gradually you become a devotee. This is natural sequence.
Ref: Lecture on Śrīmad-Bhāgavatam 1.2.12, Oct. 23, 1972, Vṛndāvana
