A.C. Bhaktivedanta Swami Prabhupada has written a song Bhakti Ahaituki Hoy Sva Prakasita and the Official Name for this song is Vrndavane Bhajana Section 19. This song is taken from the book Gaudiya Patrika. Srila Prabhupada Swami talks about madhyama-adhikar. It is due to the mercy of a pure devotee an atheist can be converted into a devotee. The Vaishnavas always delivers the afflicted soul from the material bondage. The vaishnavs are very dear to Shri Krishna.
bhakti ahaituki hoy sva prakasita
nitya siddha vastu kintu ache avarita
madhyama-adhikari vaisnava krpa to koriya
avaisnava kore krpa bhakti jagaiya
vaisnavera vasa hana svayam bhagavan
vaisnavera krpaya mugdha hoy jaguyan
vaisnava jagate pare ghumanta jagat
tan’ra i krpaya hoy papira bhakata
(1) Devotional service is causeless and self-manifesting, but the Eternally Perfect Substance is always covered over.
(2) The madhyama-adhikari (medium class devotee), being compassionate, gives mercy to the non-Vaisnavas by awakening devotion in them.
(3) The Supreme Lord is bound by the Vaisanva. By the mercy of the Vaisnavas, the bewildered can be awakened.
(4) The Vaisnava can awaken the dormat planet. With their mercy, a sinner can become a devotee.