I probably say this periodically, but I think it is appropriate to repeat (or say it publicly) while we are reading Lech l’cha. In Lech l’cha, God commands Abraham (whose name is Avram in the beginning of the story) to go to Canaan. When Avram arrives, God appears to Avram, and God promises to assign this land to Avram’s offspring. After quasi-historical episodes (the famine, the journey to Egypt, the fight between the kings, Avram’s rescuing Lot from his capturers, the birth of Ishmael, and the prophecy of Israel’s slavery), God changes Avram’s name to Abraham (and Sarai’s name to Sarah), and makes a covenant: you circumcise your male children, and I will give the land. (Actually, God three times makes the promise.)
Judaism looks a lot different from what Abraham practiced, but our tradition presupposes that Abraham practiced Judaism like we do: obeyed all the mitzvot that were unrelated to the Temple. I will say what I was alluding to in my first sentence: why did Abraham gain a following?
The Jews lived differently from everybody else in their neighborhood. They ate differently, they drank differently, they practiced sex differently, and they practiced life differently. Their neighbors had fun: they ate everything (excepting foods that were sacred), they drank, they went to the equivalent of movies on Shabbat, they had (as the Torah says) a lot of sex. Why did Abraham gain adherents to live a life a relative austerity?
Many of the Israelites’ laws became a moral standard. Why did they not join their neighbors? I am glad that they stayed apart, but to me, it is an unfathomable mystery that the Jews went their own way.