Imagine if America just went to pot, around this time (Or even just a little bit earlier). Now imagine, quite a ways into the future, site just like this. Some Christian comes into the forum, starts ranting about "Christianity is the moral guideline, and it's best way to run a country!" or some BS like that.
Then someone pipes up, "Ya, see what a great job it did on America!"
The Christian replies, "Those weren't TRUE Christians!"

Now stop imagining. Now honestly, did you laugh, giggle, or even smiled at this?
You should, because that's what a whole lot of apologists say NOW! I think it would be soooooo (some extra "o"s for emphasis) funny for these Christian-denying-Christians to go into the future and have someone say that he/she wasn't a true Christian.

But of course, even if America pulls though this. In the future there will still be cries of "Not Xian enuff!!11lol!!"

Or maybe "T3h atheist/scientist/black/muslim/evolutionist/conservative!"