Faith is primary qualification

Faith has to be there in the potency of Krishna to manifest through Vaisnavas and by having that faith that small Vaisnava, big Vaisnava, this type of Vaisnava, that type of Vaisnava, by the proper adherence of the sadacara, respect in relationship to Vaisnavas, by having faith in that principle, Krishna then gives the devotees the ability to actually see how He's manifesting shakti through that and by that association then one becomes qualified or one advances in spiritual life.
This becomes the principle that is enunciated here in this phala-stuti referring to the sloka, if you have faith, srnvata sva-katha krsna, you have to have this punya, asraddhadana munaya, the qualification for this katha is that you have to have faith in it. Then there's the other statement in first Canto, munayo sada pristhoham. Everyone has to have faith in the potency of the message, and then it will act. That becomes the adau, the preliminary, or primary qualification.

(Source: H.H. Sivarama Swami - SB 4.23.32)