CC Madhya 22.71
ekādaśa skandhe tāra kariyāche lakṣaṇa
“A devotee is considered superlative or superior according to his attachment and love. In the Eleventh Canto of Śrīmad-Bhāgavatam, the following symptoms have been given.
Śrīla Bhaktivinoda Ṭhākura has stated that if one has developed faith in Kṛṣṇa consciousness, he is to be considered an eligible candidate for further advancement in Kṛṣṇa consciousness. Those who have faith are divided into three categories — uttama, madhyama and kaniṣṭha (first class, second class and neophyte). A first-class devotee has firm conviction in the revealed scriptures and is expert in arguing according to the śāstras. He is firmly convinced of the science of Kṛṣṇa consciousness. The madhyama-adhikārī, or second-class devotee, has firm conviction in Kṛṣṇa consciousness, but he cannot support his conviction by citing śāstric references. The neophyte devotee does not yet have firm faith. In this way the devotees are typed.
The standard of devotion is also categorized in the same way. A neophyte believes that only love of Kṛṣṇa or Kṛṣṇa consciousness is very good, but he may not know the basis of pure Kṛṣṇa consciousness or how one can become a perfect devotee. Sometimes in the heart of a neophyte there is attraction for karma, jñāna or yoga. When he is free and transcendental to mixed devotional activity, he becomes a second-class devotee. When he becomes expert in logic and can refer to the śāstras, he becomes a first-class devotee. The devotees are also described as positive, comparative and superlative in terms of their love and attachment for Kṛṣṇa.
It should be understood that a madhyama-adhikārī, a second-class devotee, is fully convinced of Kṛṣṇa consciousness but cannot support his convictions with śāstric reference. A neophyte may fall down by associating with nondevotees because he is not firmly convinced and strongly situated. The second-class devotee, even though he cannot support his position with śāstric reference, can gradually become a first-class devotee by studying the śāstras and associating with a first-class devotee. However, if the second-class devotee does not advance himself by associating with a first-class devotee, he makes no progress. There is no possibility that a first-class devotee will fall down, even though he may mix with nondevotees to preach. Conviction and faith gradually increase to make one an uttama-adhikārī, a first-class devotee.