Who is a Jew?

A Jew is one who is born to a Jewish mother, or got a conversion. One of the many reasons a Jew is defined by the mother is, because we know 100% that he/she came from her, and that he/she is Jewish. The conversion is a whole process which usually takes 2, to 3 years. Anyone can convert to Judaism. People who leave Judaism for other religions are no longer Jewish-Unless they would like to return, they would not need a new conversion. A Jew that left Judaism while is still technically Jewish, may not participate in any Jewish community activities.