One should try to purchase a ticket to go back home, back to Godhead. The price of such a ticket is one’s intense desire for it, which is not easily awakened, even if one continually performs pious activities for thousands of lives. All mundane relationships are sure to be broken in the course of time but once one establishes a relationship with the Supreme Personality of Godhead in a particular rasa, it is never to be broken, even after the annihilation of the material world. — Sri Caitanya Caritamrita, Adi Lila, Chapter 01, Text 56.
Many fanatic spiritual movements have come and gone, but without the flawless philosophy of Krishna, they cannot stand. Therefore I want especially that my books and literature should be distributed profusely. This is our substance, real philosophical information, not some weak sentiments. So try for this, to give all men this Krishna Philosophy and many real devotees will come with us back to home, back to Godhead.
Even at the last moment of your life, if you remember Lord Krishna… You can go back to Godhead.
One can understand the Supreme Personality as He is only by devotional service and when he is in full consciousness of the Supreme Lord by such devotion, he can enter into the kingdom of God. — Bhagavad Gita, 18.55.
To travel in another country, you need visa permission, similarly to go back to Godhead you need permission & mercy from his pure devotee.
Without being self-controlled, without being disciplined and without being fully obedient, no one can become successful in following the instructions of the spiritual master and without doing so, no one is able to go back to Godhead.