Christianity as a social class rather than a religion.
The Achilles's heel of the ECUSA has always been its desire to be "with it," trendy, and of the times. A lot of us saw this coming as long ago as the late 60s (I would have seen it in the late 50s with Spong, but I wasn't old enough to appreciate what was going on until I was in high school.)
The Southern Episcopal Church folks saw it in 1962.
The Roman Catholic Church spotted it in 1930 (cf. Encyclical "Casti Conubii")