Śyāmasundara: What class of men did Lord Caitanya teach among?
Prabhupāda: Those who accept Kṛṣṇa as the Supreme Personality of Godhead.
Śyāmasundara: Preached among the devotees.
Prabhupāda: His preaching begins from surrendering to Kṛṣṇa. Yāre dekha tāre kaha 'kṛṣṇa'-upadeśa (CC Madhya 7.128). Kṛṣṇa upadeśa is that Kṛṣṇa is asking everyone to surrender unto Him. So one who has surrendered unto Kṛṣṇa, he can understand Lord Caitanya's teaching. Jīvera svarūpa haya nitya kṛṣṇa-dāsa (CC Madhya 20.108). He begins His teachings from the point when one accepts that "I am the eternal servant of Kṛṣṇa."
Śyāmasundara: This chanting process is directed to everyone, or just those who . . .
Prabhupāda: No, everyone. By chanting he'll come to this point. When his heart will be cleansed, then he will come to this point to surrender to Kṛṣṇa. We initiate a person, not that he is already on that standard, but we are educated him . . . educating him by the process to come to that standard.