Q. Why do orthodox Jews always think they are right? Doesn’t the Talmud say, “These, and these, are the words of the living God”?
A. It is not that orthodox Jews think they are right, but that God and His Torah are always right. When the sages said, “These, and these, are the words of the living God” (Eruvin 13b, Gittin 6b), they were speaking of two honestly held points of view within the halachah (Jewish law). Rabbinic tradition is full of examples of differing halachic views, though in the end the halachic system decided to approve one rather than another. But a non- or anti-halachic view cannot be accorded the same status as a halachic view.
It is not possible, for example, to claim that keeping kosher and not keeping kosher are equally valid. True, there are some Jews who belong to orthodox synagogues who do not (yet!) keep kosher, but they cannot argue ideologically that non-kashrut is as halachic as kashrut. The word “ideologically” is in fact the key word. The moment one puts forward an ideological claim for non-halachah one has lost the right to be counted amongst the “these and these” of whom the Talmud speaks.