Emile Durkheim decides to figure out if you can apply sociological factors to suicide. This was a revolutionary approach in his day. Of course today we understand that suicide is affect by many various factors in society but essential suicide is still considered an essentially private act of an individual often acting in isolation. Durkheim confronted the notion that suicide was essentially a psychological disfuntion in the individual. He figured that if that notion was correct he should find that people with psychological problems should be the group of people where suicide occured most often. The data simply could not support that assumption instead the data revealed that the groups of people where suicide was most prevalent were: unmarried people, Protestants (as opposed to Catholics), and men.
Based on his findings he concluded that the social factor that most affected suicide was social solidarity - the connectedness of the people with a social group.
Not sure if you noticed it but Protestants were in that top three. Durkheim said the difference between Catholics and Protestants was how the nature of their faith expression played out in communal connectivity. Catholics he suggested were more communal and their ritualistic approaches to religion kept a social contract in place. Protestants whose faith focus was on the individuals connection to God (you know personal saviour and all that), didn't seem to achieve the same social contract within thier religious expression.
I think makes for some very interesting questions for practical theology in the area of soteriology and an understanding of the nature of the church.