PAA: Zionism, Why the Big Debate?
Sure, it makes a halachic difference:
“He [The Chazon Ish] used to say: Who is an Apikores who keeps Torah and Mitzvos (“a frum Apikores”)? Someone who claims that it is the fault of the Gedolim that six million Jews were killed in Europe, and also anybody who celebrates Yom Ha’atzamut.”
http://www.hebrewbooks.org/pdfpager.aspx?req=51554&st=&pgnum=172&hilite=