The story of Avraham’s upbringing and how he came to believe in Hashem is one of the most famous omissions from the Torah. As strange as that omission is, equally as strange is where the story actually appears. While we might expect the Midrash to fill in the details, we would not expect to find that the Rambam includes this story in the Mishneh Torah, a predominantly Halachic work, where stories and homiletics are rare. In the first chapter of Hilchot Avodah Zarah, the Rambam describes in detail how idolatry developed during the generations following Adam and Chavah, and how Avraham, in his early years, began to question prevailing attitudes and find Hashem despite the dominance of idolatry.
Understanding why Avraham’s upbringing is included in the Rambam’s Halachic work can help us understand why the story is absent from the Torah and can ultimately provide a deeper understanding of Avraham’s character.
Arguably, the two most formative personalities in the Torah are Avraham and Moshe. However, the differences in their character and what they represent must be considered. While Avraham is known as Avraham Avinu, our father, Moshe is known as Moshe Rabbeinu, our teacher. While Avraham finds God, Moshe delivers God. Avraham is a man who searches and questions, while Moshe is a man who transmits Halachah, decisions, and answers.
Furthermore, although Avraham is “our father” and is considered by many opinions to be the first Jew, we find no practices of Avraham recorded in the Torah that match what we observe today on a daily basis other than Brit Milah. Wouldn’t we at least expect to find Avraham and the other Avot recognizing Shabbat, which had already been given to the world during the days of Creation!? Even further, Avraham teaches us no direct lessons. He transmits no commandments nor states directly any principles or ideas.
Altogether, Moshe and Avraham represent two very different paradigms. Moshe Rabbeinu represents fidelity to the Torah and its observance, something which is required to fully understand our responsibilities. Avraham Avinu, however, represents an entirely different paradigm and a whole different series of expectations.
Avraham represents our responsibility as Jews to search, to inquire, to be engaged, and at the same time, to be unsatisfied and restless. The story of his youth and how he went against the culture of idolatry and corruption is meant to teach us how to be restless and inquisitive within the framework of the Torah in order to deepen our faith and commitment to its ideals. Avraham does not convey these expectations directly or didactically. Rather, Avraham is a role model whose actions and words form a comprehensive paradigm for how to search restlessly and how to do so in a way that cultivates a belief in God and commitment to the core principles of the Torah. In this light, one of the most crucial verses in the life of Avraham becomes clearer. When the Torah reveals Hashem’s thinking before divulging to Avraham what will be done to Sedom and Amorah, Hashem says, "Ki Yedativ Lema’an Asher Yetzaveh Et Banav VeEt Beito Acharav VeShameru Derech Hashem LaAsot Tzeddakah UMishpat," “For I have known him, to the end that he may command his children and his household after him, that they may keep the way of Hashem, to do righteousness and justice” (BeReishit 18:19). Here is the one and only thing that Avraham is expected to “command"—that his children promote righteousness and justice. While Moshe is responsible to fill in the details, Avraham’s role in the history of the Jewish people is to be an active paradigm in the pursuit of our loftiest principles. Our responsibility is to adhere to this model of Avraham. The fact that he is referred to as “Avinu” is instructive. The difference between Moshe Rabbeinu, Moshe our teacher, and Avraham Avinu, Avraham our father, is like the difference between our communal institutions on the one hand and our homes on the other hand. Our schools and our Shuls are there to fill in all of the details contained in the Torah that Moshe teaches us. It is in our homes, though, that we are instilled with our belief in God and our commitment to the Torah's ideals. We are taught this by the example set by our parents and grandparents—the example set in the home. Our homes are the primary spheres of the paradigm of Avraham Avinu while our schools and Shuls are the primary spheres of the paradigm of Moshe Rabbeinu.
Each individual’s search, each individual’s approach to cultivating Emunah and a commitment to righteousness and justice, will be personal and different from the next person's. The written Torah is rigid and set in stone and contains the very same words each time it is opened. The oral Torah, though immutable in its content, is conveyed differently depending upon the teacher and the student and the era in which it's being taught. This is why it makes sense that Avraham’s search should be in the oral Torah, the place that reflects the notion that everyone's modeling of Avraham’s paradigm will be different.