Clarification?
I'm not positive, but what I think Ed is driving at is that at present, there are a number of "Islamic" nations in the sense that the laws of the religion take precedence over secular government. This is distinct from nations like Turkey which is largely comprised of Muslims, but is still nominally ruled by secular law.
As far as I can tell, except maybe for Vatican City, there are no "Christian" nations in the sense that the Christian religion takes precedence over all secular laws. There are, of course, many secular nations with a majority of their citizens being Christian, but that's not the same thing.
Many hundreds of years ago one could find nations ruled largely by the Church, but that hasn't been the case for a long time.