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.
Learn to feel yourself in other bodies, to know that we are all one. Throw all other nonsense to the winds. Spit out your actions, good or bad, and never think of them again. What is done is done. Throw off superstition. Have no weakness even in the face of death. Do not repent, do not brood over past deeds. Be aazaad (free).
-Swami Vivekananda