For the purposes of making Aliyah (claiming Israeli citizenship) I believe this is true. The idea is that you know who your mother is, you can't really know who your father is.
I've been told that jewishness isn't a matter of blood, therefore there is no such thing as a "secular jew".
But for those who look for these things in people, I should think that blood is blood.
My father's people were Jewish. It was concealed from me.
Allen would be barred because he's adopted another religion. elcid1970's great-grandfather wouldn't help. A single grandfather would be enough, presuming you hadn't adopted another religion, something easily lied about if one wanted to emigrate to Israel. For those who are not practicing Jews, those qualifications are based on what was necessary to be persecuted under the Nuremburg Laws.
"For the purposes of making Aliyah (claiming Israeli citizenship) I believe this is true. The idea is that you know who your mother is, you can't really know who your father is. "
No. For Halachic (Orthodox Jewish religious law) your mother has to be Jewish whether by birth or conversion, but for Aliyah different secular rules apply:
"The Law of Return attempts to provide sanctuary as a citizen in Israel to anyone who would be persecuted under the Nuremberg Laws. 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. The Law of Return merely provides citizenship for anyone covered under the Nuremberg Laws, but does not cede Jewish status to those granted citizenship."
http://en.wikipedia.org/wiki/Law_of_Return
The paternal line is used to distinguish which tribe of Israelites one belongs(ed) to. Today only three groups are recognized - Cohanim (priests), Levites, and Israelites (everyone else).