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.
If a person who lives in God becomes miserable, what is the use of living in God? What is the use of such a God? Throw such a God overboard into the Pacific Ocean. We do not want such a God!
-Swami Vivekananda