CC Madhya 19.157
aparādha-hastīra yaiche nā haya udgama
“The gardener must defend the creeper by fencing it all around so that the powerful elephant of offenses may not enter.
While the bhakti creeper is growing, the devotee must protect it by fencing it all around. The neophyte devotee must be protected by being surrounded by pure devotees. In this way he will not give the maddened elephant a chance to uproot his bhakti creeper. When one associates with nondevotees, the maddened elephant is set loose. Śrī Caitanya Mahāprabhu has said, asat-saṅga-tyāga, — ei vaiṣṇava-ācāra. The first business of a Vaiṣṇava is to give up the company of nondevotees. A so-called mature devotee, however, commits a great offense by giving up the company of pure devotees. The human being is a social animal, and if one gives up the society of pure devotees, he must associate with nondevotees (asat-saṅga). By contacting nondevotees and engaging in nondevotional activities, a so-called mature devotee will fall victim to the mad elephant offense. Whatever growth has taken place is quickly uprooted by such an offense. One should therefore be very careful to defend the creeper by fencing it in — that is, by following the regulative principles and associating with pure devotees.
Even if one thinks that there are many pseudo devotees or nondevotees in the Kṛṣṇa Consciousness Society, still one should stick to the Society; if one thinks the Society’s members are not pure devotees, one can keep direct company with the spiritual master, and if there is any doubt, one should consult the spiritual master. However, unless one follows the spiritual master’s instructions concerning the regulative principles and chanting and hearing the holy name of the Lord, one cannot become a pure devotee. By one’s mental concoctions, one falls down. By associating with nondevotees, one breaks the regulative principles and is thereby lost. In the Upadeśāmṛta (2) of Śrīla Rūpa Gosvāmī, it is said:
jana-saṅgaś ca laulyaṁ ca ṣaḍbhir bhaktir vinaśyati
“One’s devotional service is spoiled when he becomes too entangled in the following six activities: (1) eating more than necessary or collecting more funds than required, (2) overendeavoring for mundane things that are very difficult to attain, (3) talking unnecessarily about mundane subject matters, (4) practicing the scriptural rules and regulations only for the sake of following them and not for the sake of spiritual advancement, or rejecting the rules and regulations of the scriptures and working independently or whimsically, (5) associating with worldly-minded persons who are not interested in Kṛṣṇa consciousness, and (6) being greedy for mundane achievements.”