In this regard Śrīla Viśvanātha Cakravartī Ṭhākura quotes the following verse from the prayers of Lord Brahmā (Bhāg. 10.14.29):

The purport is that even though one is a very learned scholar of the Vedic śāstras, he may be completely unaware of the existence of the Supreme Personality of Godhead and His name, fame, qualities and so forth, whereas one who is not a great scholar can understand the position of the Supreme Personality of Godhead if he somehow or other becomes a pure devotee of the Lord by engaging in devotional service. Therefore this verse spoken by Yamarāja says, evaṁ vimṛśya sudhiyo bhagavati: those who engage in the loving service of the Lord become sudhiyaḥ, intelligent, but this is not so of a Vedic scholar who does not understand Kṛṣṇa's name, fame and qualities. A pure devotee is one whose intelligence is clear; he is truly thoughtful because he engages in the service of the Lord—not as a matter of show, but with love, with his mind, words and body. Nondevotees may make a show of religion, but it is not very effective because although they ostentatiously attend a temple or church, they are thinking of something else. Such persons are neglecting their religious duty and are punishable by Yamarāja. But a devotee who commits sinful acts, which he may do unwillingly or accidentally because of his former habits, is excused. That is the value of the saṅkīrtana movement.