Complex sentence: According to "halakha," a Jew by birth must be born to a Jewish mother: that is, tribal affiliation (Levite, etc.) is passed on through one's father, whereas actual Jewish identity is determined by one's mother.
Split into simpler sentences: According to "halakha," a Jew by birth must be born to a Jewish mother. Tribal affiliation (Levite, etc.) is passed on through one's father, whereas actual Jewish identity is determined by one's mother.