What is the fundamental purpose of a saint's incarnation as explained in Chapter 4?

As explained in Chapter 4, the incarnation of a saint is a selfless act performed for the benefit of humanity, not for any personal gain. The text clearly states that saints are naturally liberated beings whose incarnation is "purely for the sake of others; they have no self-interest." Their primary purpose is to respond to a decay of religion and uplift the distressed. Chapter 4 elaborates that they descend to earth to protect the humble, poor, and weak, to destroy irreligion, and to re-establish the proper systems of society. Their mission is to awaken faith and guide devotees toward the ultimate truth before ending their incarnation once their specific work is fulfilled.