God save the mark

The story

Plausibly originally a reference to the mark that a swindler fools: the swindler comments on how dull-witted the mark is and expresses a sentiment that is somewhat like God love them (God bless them, God help them) but carries the flavor of (1) may the Lord save them, because I and other sharpsters sure won't, and (2) thank God for suckers and for the fact that there's one born every minute.