Quote - Russians claim they can tell Jewish names (in Russian), but I don't know.

There's a simple rule:
Ortodox and Catholics never used names from the Old Testament., on the other side names from the New Testament are the most used.
But this no an absolute rule, if a person has a name Abraham, David, Sarah, Solomon, etc, it only means that he is not Ortodox or Catholic, but he can be Jew, Protestant or some foreigner.
If a person has a name John, Peter, Paul, Mary, etc, is very probable that he is an Ortodox, but he also can be a Jew.
There are also another rules, but I know very little of Russian language.
Stalin is not a name, is only an aka, it means as something made of steel, Djugashvilli, sounds as another aka, but I don't know what it means.
Lenin is another aka, it looks something as "lazy". Ulianov (Lenin) is from Jewish origen, the same as most of the people that made the Revolution.

Stupidity also evolves!