p.s. You may know this, but from the religious POV, you are either Jewish or not, there's no 1/8th Jewish. If your mother was Jewish, you are too, all the way up your family tree. Either that or if you converted. :)
There is no "the religious POV" and for some purposes, it seems practically and morally compelling to use a similar definition to what persecutors of Jews use, rather than a traditional religious one.
According to the Wikipedia article on Israel's Law of Return, in 1970, it was extended to people with one Jewish grandparent or married to a Jew.
"There are several explanations for the decision to be so inclusive. One is that as the Nuremberg Laws did not use a halakhic definition in its definition of "Who is a Jew", the Law of Return definition for citizenship eligibility is not halakhic either. Another explanation is the 1968 wave of immigration from Poland, following an antisemitic campaign by the government. These immigrants were very assimilated and had many non-Jewish family members."
https://www.nbcnews.com/sciencemain/all-europeans-are-relate...