Nityananda Prabhu carried out the order of Lord Sri Caitanya Mahaprabhu in this way (preaching the bhakti cult of KC and defeating all kinds of agnostics and atheistic demons), and those who strictly follow Nityananda Prabhu perform the same activities

Expressions researched:
"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"

Sri Caitanya-caritamrta

CC Antya-lila

Lord Kṛṣṇa's 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.

CC Antya 3.149, Translation and Purport

For two purposes—to spread the cult of bhakti and to defeat and subdue the atheists—Lord Nityānanda, the most dedicated devotee of the Lord, moved throughout the country.

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.