It was announced in the News that the Jewish world population has increased substantially. The article explained that due to the greater birth rate in Israel, and the redefinition of who is a Jew, the Jewish population has increased and is now equal to what it was before the Holocaust.
Wait a minute! That the Jewish birthrate in Israel is high is wonderful news, but since when do we increase the population of a certain group by redefining the group?
The Biblical definition of who is a Jew has not changed since the beginning of our history, all the way back to Avraham and Sarah. Avraham and Sarah had a son named Isaac. Avraham and Sarah's Egyptian maidservant had a son named Ishmael. If who is a Jew was determined by the father then both Isaac and Ishmael would be Jews. But no, Isaac is a Jew because his mother was a Jew (We were called Hebrews in those days) and Ishmael is Egyptian because his mother was Egyptian.
But the actual Jewish law does not come from this obvious example. The law comes from the line in the Torah that forbids a Jewish woman to marry a non-Jewish man. "You shall not intermarry with them (non-Jews); you shall not give your daughter to his son, and you shall not take his daughter for your son, for he will cause your child to turn away from Me and they will worship the gods of others…" [i]
The Torah says not to intermarry your daughter or your son, but the reason why we are not to intermarry is because he (the non-Jewish man with your daughter) will turn your (grand) child from Hashem. The Torah could very well have said that "they (both the non-Jewish woman and the non-Jewish man) will turn your child away" but it only says "He will turn your child away." The child of your daughter, even from a non-Jewish man, is called your child. But the Torah does not say that the non-Jewish girl will take your child away because her offspring, even with your Jewish son, are not yours, i.e. they are non-Jews and belong to the tribe of their mother.
We do not get more elephants in the world by calling hippopotamuses elephants.
[i] Deuteronomy 7:4