Several christians say that the influence of christian ideas on culture is proof of the "truth" of christianity, that christianity is being divinely preserved. To hold this idea, they refer to expressions and various cultural tidbits that can be traced back to a christian, even if the wording has since been changed.
This raises an interesting issue. The old Greek beliefs are also preserved -- with less modification. Of course, we have the Olympics, which were a deliberate restoration. (Why did unbelievers restore the Greek tradition?) It requires little effort to find things named for the elements of the belief. Google any of the Greek gods. (Okay, I didn't do an exhaustive search. But come on, you can find a book publisher named Persephone.) The christian has actual followers; but I would venture that it is the one more likely to be forgotten someday.