Who is a Judaist?

It is critical to know who to consider as an Israelite because the Torah is primarily about our obligations to fellow Israelites.  In biblical times, knowing who was a Israelite wasn't an issue because Israelites lived together as a nation.  If you lived with the Israelites and accepted the Israelite god, then you were an Israelite.  But once Israelites were dispersed and often lived as a religion within an empire, it became unclear who exactly was a Israelite.

Rabbinic Judaism treats Jews as Israelites where being a Jew is primarily an ethnic category.  Talmudic Judaism defines a Jew as one with a Jewish mother.  Today, different branches of Judaism answer the question of who is a Jew differently.  Reform Judaism says that either parent being Jewish makes the child Jewish.  Karaite Judaism defines a Jew as one with a Jewish father.  Humanistic Judaism defines a Jew as "someone who identifies with the history, culture and fate of the Jewish people."  For more, see Wikipedia.

The idea of defining a Israelite by the parents has no basis in the Bible.  It seems mildly racist.  And it violates the focus on action in the Bible.  For example, Exodus 31:14 says that whoever does work on the Sabbath must be cut off from his people.  This implies that to be a Israelite requires certain actions.  Humanistic Judaism rejects defining a Jew by their parents, but still doesn't choose actions as the alternative.  Their definition is also vague.

Biblic Judaism takes a different approach.  We consider a Judaist as an Israelite where a Judaist is someone who actually practices some meaningful form of Judaism.  We are not concerned with ancestry.  An ideal definition of a Judaist would be based on actions that are easily testable.  So while "do not commit adultery" is a commandment, it is a poor test.  Are you going to ask people "do you commit adultery?" and expect an honest answer?  Biblic Judaism has chosen for its 5 core practices actions that are simple and clearly testable.  Biblic Judaism defines a Judaist as one who follows these 5 core practices.

For reference, our five core practices are:

1.  Support other Judaists.
2.  Keep shabbat.
3.  No tattoos.
4.  Dress modestly.
5.  Wear tzitzit.

Is a Reform Jew a Judaist?  Probably not, he probably doesn't follow some of these practices.  So we wouldn't consider him a Judaist.  What about an Orthodox Jew?  The main issue that Orthodox Jews have is with requirement #1.  Orthodox Jews who don't support other Judaists in synagogue are not Judaists themselves.  What about a Karaite Jew?  If he keeps the practices, then yes, otherwise no.  What if the Karaite keeps the practices but doesn't agree with anything else we do and believe?  That doesn't matter, he is still a Judaist because he keeps the core practices.

What about someone from a completely different religion, is he Judaist if he keeps the core practices?  This is a silly and meaningless question because it simply won't happen.  He has no reason to keep the practices, so he won't.