By associating with holy persons and discussing transcendental subject matters with them, one becomes convinced of the value of spiritual life. Very soon, hearing of Kṛṣṇa becomes pleasing to the ear and begins to satisfy one's heart. After receiving such spiritual messages from holy persons, or pure devotees, if one tries to apply them in his own life, one naturally and successively develops faith, attachment and devotion while progressing on the path of Kṛṣṇa consciousness.
The Lord then informed Sanātana Gosvāmī about the behavior of a devotee. The sum and substance of such behavior is that one should always stay aloof from unholy association. And what is unholy association? It is association with one who is too much attached to women or one who is not a devotee of Lord Kṛṣṇa. These are unholy persons. One is thus advised to associate with holy devotees of the Lord and carefully avoid the association of unholy nondevotees. Pure devotees of Kṛṣṇa are very careful to keep aloof from the two kinds of nondevotees.