Why did the central teachings of Judaism survive to the modern day?

Answer 1

There are numerous interrelated reasons that the Jews and their religion survived despite being deprived of their homeland and being almost consistently persecuted to varying degrees, regardless of whether the miracle-argument is convincing or not.

1) Identity and Distinctiveness: Both Jews and non-Jews perceived Jews as a unique ethnic group of people with specific religious beliefs. Historically, parts of the Jewish and parts of the non-Jewish communities have strongly resisted integration and legal equality between Jews and non-Jews. This distinctive identity was further reinforced by the various forms of persecution that Jews suffered. They realized that nobody would look out for their interests consistently other than themselves, which made them more resilient and inward-looking as a community with distinct customs and beliefs.

It is worth noting that in countries with more persistent persecution (but not genocide) of Jews, that Jews tend to be more religious than in countries were Jews feel less persecuted. This is not to encourage persecution, but there is a strong correlation between stronger persecution (that does not rise to genocides or massacres) and a more religious Jewish population.

2) High Degree of Literacy and Education: Jews have historically had high literacy rates and a determination to be educated. This resulted in Jews being able to more effectively preserve their traditions than the general Christian or Muslim populations with which they lived. This prevented cultural diffusion, where it did occur, from obfuscating Jewish traditions because the latter could always be reread and discussed.

3) Usefulness: Since Jews were more educated, they were able to branch out into numerous more skilled professions. Additionally, many of the professions in artisanry were forbidden to Jews. This led to many Jews becoming lawyers, doctors, bankers, and bureaucrats. Their abilities to help Gentile leaders effectively rule their states made the Jews worth protecting in a way that other minorities, such as the Romani who were much less useful to Gentile leaders, did not encourage.

4) Mobility: Unlike most minorities, the Jews were able to migrate from areas with increasing persecution and hardship to areas where these things were lessened. This moblity was enhanced by the above three benefits. Since Jews were distinct, it fostered a strong sense of brotherhood, meaning that a migrant Jew would be welcomed by the extant Jewish community. Additionally, the shared literacy of the Jewish communities meant that even if the migrants did not speak the vernacular, they could at least communicate with Jews using written Hebrew in a pinch. However, more useful were Jewish languages like Yiddish, Ladino, Yevanic, or Judeo-Arabic which had a larger geographic dispersions than most spoken languages of the time. Also, given that Jews were very useful, they posed less of welfare problem than non-Jewish migrants with equal resources.

Answer 2

Because of God's covenant. Any other explanation is insufficient. The same goes for the famous question of how we Jews have survived for so long.
Rabbi Jacob Emden (1697-1776) once said that the survival of the Jewish people is the greatest of miracles.
Consider also this famous quote from Mark Twain:
"If the statistics are right, the Jews constitute but one quarter of one percent of the human race. The Jew ought hardly to be heard of; but he is heard of, has always been heard of. The Egyptians, the Babylonians and the Persians rose, filled the planet with sound and splendor, then faded to dream-stuff and passed away; the Greeks and Romans followed and made a vast noise, and they were gone; other people have sprung up and held their torch high for a time but it burned out, and they sit in twilight now, or have vanished.The Jew saw them all, survived them all, and is now what he always was, exhibiting no dulling of his alert mind. All things are mortal but the Jews; all other forces pass, but he remains. What is the secret of his immortality?" See also:

God's covenant

Keeping Judaism strong during exile

What did Rabbi Yohanan ben Zakkai do for the survival of Judaism?

Answer 3

The teachings of Judaism have evolved over the centuries. Some teachings from the monarchical period and central to Judaism have survived more or less as originally formed, but many others have evolved or disappeared. Mark S. Smith (The Early History of God) says that according to the available evidence, Israelite religion in its earliest form did not contrast markedly with the religions of its Levantine neighbours in either number or configuration of deities. He says that in the Judges period, Israelite divinities may have included Yahweh, El, Baal and perhaps Asherah as well as the sun, moon and stars. He adds the goddess Astarte for the monarchical period.
Nevertheless, during the late monarchical period, Judaism became monolatrous (accepting the existing of more than one god, but worshipping just one God) and then, finally, monotheistic. Until the destruction of the Jerusalem temple in 70 CE, animal sacrifices remained the central ritual, and therefore key to the central teachings of Judaism.

Randall Price (The Secrets of the Dead Sea Scrolls) cites Dr. Lawrence Schiffman as saying, "Second Temple Judaism can now be seen as a transition period in which the sectarianism and apocalypticism of the period gradually gave way to rabbinic Judaism, on the one hand, and Christianity, on the other. Indeed, it is now clear that the Second Temple period was a kind of sorting out process." John Dominic Crossan (The Birth of Christianity) says that although rabbinic Judaism, the post-70 CE development of Judaism, claimed exclusive continuity with the past, in truth it was a great leap from that ancestry, as much as was Christianity.

Lee I. A. Levine says that after 70 CE, new themes crystalised - the kingship of God, remembrance and redemption - and appropriate blessings and prayers were formulated. Special scriptural readings were introduced, along with a special ceremony for the blowing of the shofar.

The earliest known complete Hebrew manuscript of the Old Testament was the Ben Asher codex in the Public Library of Leningrad, dating to about 1008. The Septuagint and the Dead Sea Scrolls provide two incomplete windows into Jewish beliefs in the late Second Temple period and comparisons show that changes have occurred. Price says some scholars now feel that the Old Testament canon was not as fixed as had been previously believed. Rather, the construction of the canon was a process that occurred gradually over time and involved many more people than envisaged before the Scrolls were discovered. They also believe that the canonical process was never viewed with complete unanimity among the various sects of Second Temple Judaism, even as it has not in Christendom until today.

Centuries after the time of Christ, the process of interpreting the Scriptures was called midrash (exposition). This was commentary that stated rabbinic interpretation of the law arranged according to the order of the biblical text. Hershel Shanks says (Christianity and Rabbinic Judaism) some midrashim make obvious references to the period after the Islamic conquests.

So it is in the nature of an urban myth that the central teachings of Judaism have survived unchanged for millennia. Judaism has survived and flourished while other great religions have disappeared, but in doing so it has adapted and altered some of its most basic teachings.