While it is true that the religion of Judaism today has strayed far from the Mosaic Law, it is also true that Judaism has many branches. Orthodox Jews seem to practice more of a rabbinical religion than the Truth handed down from G-d. But there are also Messianic Jews who follow the Truth of the L-rd and have accepted G-d's Messiah Y'shua. Then there are many Jews who are simply secular and are unfamiliar with their own backgrounds. There is a wide variety of Jewish People.
The word Jew is simply a shortened form of Judah (Praiser of G-d).
One thing I know -- G-d promised that the entire world would be blessed through the seed of Abraham, Isaac and Jacob and it is: we have the Written Word and the Living Word given through the Jewish People.
We also have a promise & a warning from the L-rd - those who bless His people will be blessed, those who curse them will be cursed. (Genesis 12)
The L-rd never told the Jewish People not to mix their seed with others, but not to intermarry with those who do not believe in G-d. Just look at the geneaologies in the Bible and you will see many believers "grafted in", like Ruth.
The person who wrote the article is a little confused about history. The simplicity of the Bible is wonderful and the Holy Spirit of G-d is there to help you understand it - Just ask! G-d is not finished with the Jews and Prophecy is being fulfilled today as He draws His ancient People back to the Land! The 70th "week" of Daniel is yet to be fulfilled. These are exciting days to be alive; don't allow someone to steal your Joy in the Lord by a lot of argumentative and confusing articles. Look up! Your redemption draws near!