Anyone born to a Jewish mother or accepted to Judaism through official procedures is a Jew.
An important point is that being Jewish is not about belief or behavior. A person whose parents are not Jewish, but who thinks and lives like an Orthodox (religious) Jew and fulfills every commandment of Judaism, is not considered a Jew even in the eyes of the most liberal Jews, if he has not gone through the formal procedure required to convert to Judaism. On the other hand, if a person is born to a Jewish mother, even if he does not practice the Jewish religion or is an atheist, he is considered a Jew even in the eyes of the most religious Jews. For this reason, Judaism may sometimes be perceived as a nationality rather than a religion, and being Jewish may be perceived as a nationality.
Converts and conversion are seen in the early periods of Judaism. The Torah includes terms such as “strangers living among you,” “honest converts,” or “honest foreigners.” These are people who live among Jews but are not Jews, and who have adopted and practiced all or part of the Jewish faith and its requirements without officially changing their religion. After converting to Judaism; the person is now as much a Jew as anyone born Jewish.
