Joyful Surrender is related to the goal of our existence: to realize ourselves as the Atman, the eternal spirit.
Kriyananda describes the principle of yagya which means sacrifice. Sacrafice is essential if we want to succeed in our spiritual endeavors. If we want to be truly free, it is important to surrender all that we are to God.
There are two ways to approach God described in the the ancient teachings of India: impersonal and personal. The personal approach, with a human representation of the Infinite, is a way to make the divine connection real, such as with Radha and Lord Krishna. Their relationship represents spirit and nature dancing together.