Why is judaism considered ethnic?

Answer 1

In classical Jewish sources such as the Torah, Jews are spoken of as a nation, with Judaism being their national code of living.
Today, many speak of Judaism as both a religion and an ethnicity. It's an ethnicity because Jews are descended from Abraham, Isaac and Jacob and their wives: Jews, despite their diversity, are related to each other (as has been shown by DNA analyses of far-flung Jewish communities). And it's a religion, because Judaism is defined in dictionaries as the religion of Moses; the religion of the Torah, which includes people born Jewish as well as non-ethnic Jews who became converts.