Martin Marty defines pluralism -- and substance of his work -- in 2006 ACLS "Life of Learning" lecture

The "Life of Learning" lectures are an annual series sponsored by the American Council of Learned Societies in which scholars are asked to "to reflect on a lifetime of work as a scholar and an institution builder, on the motives, the chance determinations, the satisfactions (and dissatisfactions) of the life of learning, to explore through one's own life the larger, institutional life of scholarship." Toward the end, church history professor Martin Marty sums up one of the key themes of his historical writing:

The question of substance -- voiced as "what was and what is your historical work about?" -- receives a simple answer. It is telling a story of American religion, a story that has continued unfolding in new contexts and with new emphases through 50 years. Decades ago, during a long strenuous slog on a Manhattan avenue during a snowstorm, cabs that day having been unresponsive to hailing, my publisher-to-be asked about my plot: what did I think American religion was about? "Pluralism," I responded between a huff and a puff, while thinking of America's unmatched varieties of faiths and polities. He snorted: "You couldn't be more wrong! That is what social scientists think, but religious people themselves have other things beside abstractions on their minds." Those odd "other things" turned out to be the lure for my re- search, even if they have to be accounted for under the abstract blanket of "pluralism." (18)

Martin Marty. "A Life of Learning." Charles Homer Haskins Prize Lecture for 2006. ALCS Occasional Paper No. 62. American Council of Learned Societies. http://www.acls.org/Publications/OP/Haskins/2006_MartinEMarty.pdf