Naya-kovidāḥ means nyāya-nipuṇa. Bhagavad-dūtas, those who are gosvāmīs, they place everything with nyāya, or logic. Their instructions are not blind, dogmatic. Naya-kovidāḥ. Everything what is said by Kṛṣṇa or His representative, they are not dogmas. Those who are not representative of Kṛṣṇa, they will say simply dogmas. Just like in every religion there is a dogma. But in bhāgavata religion, bhāgavata-dharma, there is no dogma.
Caitanya Mahāprabhu's bhāgavata-dharma, the Caitanya-caritāmṛta's author, Kṛṣṇadāsa Kavirāja Gosvāmī, says therefore that caitanyera dayāra kathā karaha vicāra (CC Adi 8.1). Vicāra means you just try to understand the gift of Lord Caitanya by logic, vicāra. Don't follow blindly.
Following blindly something, that is not good. That will not stay. But one should take everything with logic. But the servants of God, they put everything in logic. Caitanyera dayāra kathā karaha vicāra. If you study the Caitanya's philosophy with logic and argument . . . don't go by sentiment.
The so-called missionary, they're simply bogus propaganda, without any logic. Without any logic. Just like some missionary people are propagating a man to become God. How a man can become God? There must be evidences how God incarnates. Not that somebody by worshiping a demigod becomes God. So many false propaganda is going on. That is not logical at all.
So one should be intelligent to understand the philosophy of Kṛṣṇa or philosophy of Lord Caitanya with logic and argument. Don't follow blindly. But once you accept, you cannot argue. You have to accept blindly. But before accepting, you take to logic. But when you accept, then don't go back. Then that is falldown.