Is the Mosaic Covenant Irrelevant?

Jennifer Green of Baton Rouge wrote the following:

As evidenced by two recent letters, both of which argue that so-called “Messianic Jews” are Jewish, there seems to be ongoing confusion about the differences between “Messianic Jews” and mainstream Jews, whose members can be roughly divided among the Orthodox, Hasidic, Reform, Conservative, Humanistic and Reconstructionist movements within Judaism.

What all these Jewish denominations have in common is a belief system based on Covenant — that which God gave Israel, through his prophet, Moses, at Sinai.

“Messianic Jews” — also known as “Jews for Jesus” — have rejected this covenant as irrelevant, replacing it with belief in Jesus.

Rejected as irrelevant?

Who says that?

Read what the apostle Paul (Saul of Tarsus) wrote in Romans:

Do we then overthrow the law by this faith? By no means! On the contrary, we uphold the law.