There is a great article in this month's Book's and Culture magazine summarizing a book by Arthur Brooks entitled Who Really Cares? The work studied the difference between religious conservatives and secular liberals in the area of charitability. Here is a summary from the article:

Religious Americans are not only much more likely to give money and volunteer their time to religious and secular institutions, they are also more likely to provide aid to family members, return incorrect change, help a homeless person, and donate blood. In fact, despite expecting to find just the opposite, Brooks concluded: "I have never found a measurable way in which secularists are more charitable than religious people."