Lev Grinberg confuses two independent issues: the definition of Judaism with the politics of Judaism. About the definition, even the official Israeli definition is not religious as it says that a Jew can be simply someone who was born to a Jewish mother. This makes it into a historical definition, since it might just as well be that none of my ancestors were religious although the lineage goes back to (say) Mount Sinai. Also, this definition can explain why a Jew cannot be Muslim or Christian as those involve adopting another historical affiliation (the one originating in Christ or Muhammad). About the politics of Judaism, this has nothing to do with Zionism but with post-Zionism(!) and the hegemonization of Israeli society by orthodox and traditional Jews. In other words, the less colonialist Israel becomes, that is, the more it integrates into the region, the more like its Arab neighbors it becomes and thus, less liberal.
Germany's Merkel backs justice minister in dismissal of top prosecutor (DPA)
from the article: You can't be a Jewish Muslim