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.
The weak, the fearful, the ignorant will never reach the Atman. You cannot undo what you have done; the effect must come. Face it, but be careful never to do the same thing again. Give up the burden of all deeds to God. Give all, both good and bad. God helps those who do not help themselves.
-Swami Vivekananda