There are different opinions about how old Avraham was when he first recognized Hashem. Rambam (Hilchos Avodas Kochavim 1:2) writes, "Avraham was forty years old when he recognized the Creator..."
The Raavad notes, "There is a Midrash that says he was three years old."
Another Midrash states that Avraham recognized Hashem at the age of forty-eight. The Sar Shalom of Belz zt'l said this opinion needs clarification. The opinion that Avraham recognized Hashem when he was three years old is understood: When Avraham was at the age of basic comprehension, he already recognized Hashem. Also, Rambam’s opinion that Avraham was forty years old is understood because לבינה ארבעים בן, at forty, one attains understanding and perception. But what’s the significance of forty-eight? (And we can't say it was just by chance since we know that nothing ever happens by chance. Certainly not when discussing the avos and the fundamental issue of when Avraham attained emunah.)
The Sar Shalom explains that when Avraham was forty-eight, the infamous Tower of Bavel was being built, an edifice that represented heresy and rebellion against Hashem. The spirit of the entire generation was one of heresy and rebellion. The rule is that when one acquires emunah at a time when it’s difficult to do so, the emunah becomes very deep and sincere. Since Avraham attained his emunah when many people were leaning towards heterodoxy, he achieved a profound and sincere level of emunah.
We too live at a time when it is difficult to have proper emunah. Rebbe Yisrael of Ruzhin zt'l compared believing in Hashem in the generation before Moshiach to the difficulty of climbing up a straight wall. Rebbe Elimelech of Lizensk zt'l compared it to holding onto a rope suspended from heaven. The rope is shaken violently, and only those grasping onto the rope with all their strength will survive.
We live in a time of great challenge, but those who cleave to Hashem with all their might at this time will reach great heights and perfect clarity in emunah.
Hashem told Avraham (15:5) השמימה נא הבט זרעך יהיה כה לו ויאמר אתם לספר תוכל אם הכוכבים וספר , "Look up to the heaven and count the stars, if you can count them.' Hashem said, 'So shall be your offspring.'"
In which way does the Jewish nation resemble the stars? Stars shine at night, and likewise, the specialness of the Jewish nation emerges when it is dark. In a spiritual context, this means that from tests and challenges of the yetzer hara one rises to greater heights. Avraham reached perfection in emunah due to the tests. Similarly, every Yid attains perfection in his emunah and all aspects of his character and avodas Hashem through his tests and struggles.
