As a European I can tell you that Croatia is not considered part of Europe proper. Its where we go for vacations and cheap booze.

It doesn't matter that they're white and Christian. They're Slavic or Balkan which means they're not "european" in the common conception.
Same goes for Slovenia.
The Czech kind of get an on/off perception of wether or not they're European. The Czechs are mad about this, since they are very obviously "culturally" european, however they're also an old east block country, which makes them slabs, which means they cannot possibly be real europeans.