How did the ancient religion of judaism survive into modern times?

Answer 1

1) Through the stiff-necked behavior of the Jewish people (Exodus ch.32), who steadfastly refused to relinquish their religion. 2) Through the promise of God (Genesis 18:19).

Rabbi Jacob Emden (1697-1776) once said that the survival of Judaism and the Jewish people is the greatest of miracles. It can be explained only as a fulfillment of God's covenant.
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?"

Answer 2

Rabbi Jacob Emden (1697-1776) once said that the survival of the Jewish people is the greatest of miracles. It can be explained only as a fulfillment of God's covenant.

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 then 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

There are numerous interrelated reasons that the Jews 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, 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 mobility 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 dispersion 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.