Sri Chaitanya Mahaprabhu showed by his personal life the validity of the doctrines of devotion described in Srimad Bhagavata. Holding Achintya-Bheda-bheda or identity-in-difference to be the nature of the Ultimate Reality whom he called Sri Krishna, Chaitanya demonstrated how Bhakti is the sure way to higher spiritual development.
Seek ye first the kingdom of God, and everything shall be added unto you. This is the one great duty, this is renunciation. Live for an ideal, and leave no place in the mind for anything else. Let us put forth all our energies to acquire that which never fails--our spiritual perfection. If we have true yearning for realization, we must struggle, and through struggle growth will come. We shall make mistakes, but they may be angels unawares.
-Swami Vivekananda