Is "secularism" going mainstream?

This week's Newsweek includes a right-on column by religion editor Lisa Miller defending the term "secularism" against its critics (among whom she includes Harvard's humanist chaplain, Greg Epstein--but see here). Miller contrasts secularism with nontheism and underscores its positive meaning:

"Secular" was first used in the Middle Ages to mean things and people not belonging to the church—as Webster's puts it, "not overtly or specifically religious; not ecclesiastical or clerical." This remains its best and most important meaning. In this great experiment that is American democracy, "secular" is the only word we have to describe the idea, handed down by the Founders, that our leaders do not belong to God, they belong to us.

In this sense, we're all secularists now.