OR:
4. A year of immersion in the relentless 24/7 “gay marriage” propaganda (quite possibly culminating in the eradication of DOMA) has swept away a large number of shallowly rooted believers who have rejected their superficial faith under the incessant barrage of Christian bashing.
I don't think that there was a huge swing in the number of Christians in the past 12 months. If the poll is true it is just the chaff falling away from the wheat.