As stated in the Bhagavad-gītā (BG 4.8):
- paritrāṇāya sādhūnāṁ vināśāya ca duṣkṛtām
- dharma-saṁsthāpanārthāya sambhavāmi yuge yuge
Lord Kṛṣṇa appears in every millennium for two purposes, namely to deliver the devotees and to kill the nondevotees. His devotees also have two similar purposes-to preach the bhakti cult of Kṛṣṇa consciousness and to defeat all kinds of agnostics and atheistic demons. Nityānanda Prabhu carried out the order of Lord Śrī Caitanya Mahāprabhu in this way, and those who strictly follow Nityānanda Prabhu perform the same activities. There are two classes of devotees. One is called goṣṭhy-ānandī, and the other is called bhajanānandī. A devotee who does not preach but always engages in devotional activities is called a bhajanānandī, whereas a devotee who not only is expert in devotional service but who also preaches the cult of bhakti and defeats all kinds of agnostics is called a goṣṭhyānandī.