I don't know about Germany ... but Afrikaans-speaking South
Africa is firmly Protestant and mostly Calvinist, and both
Calvin and
Luther are used as boy names, with
Calvin often spelled Kalvyn to fit into the modern language.I've known English-speaking South Africans called
Calvin too; never a
Luther, but I might have missed a few :)
We have a strong tradition of using surnames as given names, for family or personal reasons mostly, not because of fashion. Our early Dutch settlers had a very small pool of names, both surnames and given names, to choose from so they had to find creative ways of combining them.So it would be impossible to legislate against it!