What percentage of Jews in Israel are atheist?

Judaism is an ethnic group as well as a religion, so there are Jewish atheists, but statistics are not measured on this category. Some Jewish Atheists prefer to be called Humanistic Jews, and there are even synagogues dedicated to humanistic Judaism.

Judaism isn't just about religion. It's about culture, family and traditions. You are considered Jewish if you were born of a Jewish mother.

Reform Judaism includes more in the fold. I know many atheists who participate in Jewish holidays and traditions because it is important to them. You can do that, and not believe in God.

Israeli answer:

Only 40% of Israelis define themselves as secular; and even among those, many believe in God.