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.
Be brave! Be strong! Be fearless! Once you have taken up the spiritual life, fight as long as there is any life in you. Even though you know you are going to be killed, fight till you are killed. Don't die of fright. Die fighting. Don't go down till you are knocked down.
-Swami Vivekananda