What really counts is that a state should be able to provide equality to all of its citizens regardless of their ethnicity or religion. Israel has no constitution, nor any anti-discrimination legislation. Israel defenders often state that Israel has an independent judiciary but so court decisions mean nothing if they are not given effect - as happens in Israel. So just would be non-Jews be confirming if they agree to this oath? Until you come up with a definition of Jewish this oath can bring trouble - you may think that "Jewish" covers the orthodox, etc but will it also cover the converted - will they be 'Jewish" enough for Israel? No state which has an oath for new citizens requires them to confirm either a race or a religion - merely to uphold law etc.
from the article: The Jewish Republic of Israel