Born in Cleveland, Ohio, Miller was raised in a secular Jewish home. She attended Oberlin College in Oberlin, Ohio, graduating in English in 1984. She worked at the Harvard Business Review, The New Yorker, and The Wall Street Journal.

Miller was married to her husband in an interfaith ceremony performed by an Episcopalian priest who worked with a rabbi on the ceremony. After the birth of her daughter, Miller joined a Jewish Temple for reasons of "blood and history and culture". She describes this religious community as a "progressive, inclusive congregation."

Miller joined Newsweek as Society Editor in July 2000, becoming the Religion Editor and columnist in October 2006. Miller also is a regular contributor to the Washington Post's On Faith blog.