tomaara se prema-bhakti
vinaa tumi dile kaaro
bhakti naahi haya
Lord Gauranga Himself roared and proclaimed in Sri Chaitanya Bhagavata 2.5.100:
"Oh Nitai, in this whole creation, Prema Bhakti is only Your property and no one else's!!!
"It is thus only possible because of You and no one else.
"You are also the cumulative personification of all Prema Bhakti and Prema Bhaktas in the whole creation.
"So without You explicitly giving this (Gaura Radha Krishna) Bhakti to a soul, no soul in the whole creation can ever get any true Bhakti."
Inspite of hearing this truth from Lord Gaura's lotus mouth, souls full of pride think of themselves as "big qualified devotees" and shamelessly jump over the head of Nitai Bhakti by having the audacity to directly practice Gaura Bhakti or Radha Krishna Bhakti, even after reading and hearing such unequivocal and repeated proclamations from Lord Gaura Krishna Himself in Sri Chaitanya Bhagavata.
So who can ever make them see the truth?
Who can ever correct the misuse of their free will?
We can awaken those who are sleeping but we can never awaken those who are pretending to sleep, i.e. those who see these crystal-clear orders of the Supreme Lord Gaura to worship only Lord Nitai for Prema Bhakti, yet they don't want to see or accept them by taking full shelter of Nitai Bhakti.
This is due to them remaining totally blinded by their false ego, which keeps them in an offensive state of illusion that they can directly approach Gauranga, Radha Krishna, or Shuddha Harinama without patiently practicing Nitai Bhakti. Alas!!! Alas!!!
ahankare matta hoiya, nitai-pada-pashariya...
When Lord Gaura states: vinaa tumi dile kaaro, bhakti nahi haya... He clearly means that even He does not give Bhakti to anyone directly. He awards Prema Bhakti to a soul only through His beloved brother Nitai.
This is not just a one-off proclamation by Lord Gaura. It is confirmed by many of His other similar proclamations like the one below:
amara sakala karma, nityananda dvare (CB 3.5.103) - "All of My actions, including the distribution of My own Prema Bhakti, happen only through My Nitai, no one else, not even through Me directly."