Vaishnava Samhita. Chaturbhujadasa Charitam. Vol III Book VII Chp 12 Shlokas 9 - 10

दुर्लभं मानुषं जन्म वैष्णवत्वं सुदुर्लभम् |

तत्रापि राधिकानाथे प्रेमभक्तिः सुदुर्लभा ||

केनापि पुन्यपुञ्जेन वैष्णवत्वमवाप्य च |

देवतान्तरभक्तिं हि यः करोति स दुर्भगः ||

It is very difficult to attain birth as a human being. It is all the more difficult to be a vaishnava. It is utmost difficult to develop prema bhakti towards Shri Krishna, the beloved of Devi Radha. He is the most unfortunate person who is born in a vaishnava family due to some unknown good fortune, and yet develops devotion to gods other than Shri Krishna.