NYU professor Jason Franklin has categorized charitable giving into 6 motivators: faith, enthusiasm, making an impact, fairness, simplicity, and...joy.
"With all this giving going to religious groups, it may appear that religious people are more charitable than non-religious people. But are they? When experts familiar with charitable giving look at the reasons for giving, they find a complex mix of motivations — some that fit tightly into religious life, and others that are less so." -- Michael De Groot, the Deseret News