I'd like to begin by saying that I have great respect for the Rabbi's & Sage's of our people. Having said that, we must remember that they are men, not G-d, and are capable of error. While many in the Jewish community want to treat Rabbinical decisions as equal to the Word or G-d, we do not agree with that level of authority. We see the Rabbi's and Sages as learned, wise men, providing commentary on scripture. We also view the Oral Torah as Commentary, not having the weight of G-d breathed scripture. This is very similar to how Protestants view the Catacism.
Rabbinical statements which stray:
1. In 132 CE, Rabbi Akiva named Simon Bar Koshba (son of a liar) the Messiah, renaming him Bar Kochba (son of a star). The result, in 135 CE the revolt ended, 1000's were killed, Jerusalem was destroyed and rebuilt as a Pagan city.
2. RamBam in His 13 articles of Faith declared G-d yachid, not echad. Yachid means the only one, not one as scripture states. Why the big deal, this was done to counter the concept of Messiah as G-d. Echad means simple one, and is used in B'rsheet to say Adam & Eve became one. Thus two became one flesh.
Rabbinic statements have tremendous impact in the Jewish Community. We must be knowledable enough to know the origins of these statements, and show, using Hebrew texts, the problems they create.
Blessings in Messiah