Sat-sanga is the only cause for the prime benediction of the jiva. Therefore, our beloved Sri Caitanya Mahaprabhu instructed Srila Sanatana Gosvami that sat-sanga was teh seed and the root of suddha-bhakti, whereas teh company of bhogis, sense-enjoyers, and asat-sanga, non-devotees, was destructive and should be rejected. Sri-krsna-nama must be chanted in sat-sanga.
Jaiva Dharma chapter 25 (pg 387 of the Brhat Mrdanga Press edition)