Different parts of the human body work together,allowing us to function effectively. Our existence and survival depend on cooperation and coordination of these parts. Take for instance, the human family.
In the absence of cooperation and understanding, parents and children are always fighting. The same is true quarrels between couples. Cooperation is imperative for a healthy family,body,society and nation.
How does one develop cooperation? Voluntary actions, altruism and showing concern for others. These need not be considered sacred; they are in ones own interest.
If one understands that Mother Teresa own "Darkness" was directly related to theses sobering facts of human life,conditions she faced daily and unblinkingly ,one can also begin to understand, or at least intuit, how this was inevitably related to her faith.
Diverting energy and social resources away from needed efforts to remedy the world's suffering can seem unjustifiable. But This argument is countered by noting that happy people are found to be more willing and able to dedicate themselves to altruistic actions on behalf of relieving suffering