“…R’ Yirmiyah said in the name of R’ Shmuel bar Rav Yitzchak: We find that G-d excused the Jewish people for idol-worship, adultery, and murder, but their contempt of the Torah He did not excuse. What is the proof? It is not written here, “And G-d said, ‘Because they committed idol-worship, adultery, and murder,’” but “And G-d said, ‘Because they abandoned My Torah’ (Yirmiyahu 9:11).” Said R’ Chiya bar Ba, “They abandoned me” (Yirmiyahu 16:11)—I will excuse it. But if only “they guarded My Torah” [see Yirmiyahu, ibid). For if they abandoned me but guarded My Torah, the light within it would have brought them close to Me…” – Talmud Yerushalmi, Chagigah 1:7

ר’ ירמיה בשם ר’ שמואל בר רב יצחק מצאנו שוויתר הקדוש ברוך הוא לישראל על עכו”ם ועל גילוי עריות ועל שפיכות דמים על מאסם בתורה לא וויתר מה טעמא ויאמר ה’ על אשר עשו עכו”ם וגילוי עריות ושפיכות דמים אין כתוב כאן אלא ויאמר ה’ על עזבם את תורתי א”ר חייה בר בא אותי עזבו אוותרה שמא את תורתי שמרו שאילו אותי עזבו ותורתי שמרו המאור שבה היה מקרבן אצלי – ירושלמי חגיגה א, ז

The Sages of the Talmud (Bava Metzia 85b; Yerushalmi Chagigah 1:7) taught that the first Beis Hamikdash, the Holy Temple in Jerusalem, would have been spared from destruction if the Jewish people would have respected and valued Torah study. Despite the other sins prevalent among the Jewish people of that era, if they had valued the Torah, the luminescence of the Torah would have restored their relationship with G-d.

The destruction of the second Beis Hamikdash, however,was caused by senseless hate among the Jewish people (see Talmud, Yoma 9b).

In light of the above, our efforts to restore the Beis Hamikdash through “repentance and good deeds” (see Talmud, Sanhedrin 97b) must focus on these two areas in particular: love of our fellow Jew, and developing a deeper appreciation for the Torah and its commands.

These two efforts converge when we endeavor to strengthen other Jews in their Torah study and observance. For there is no greater act of love than to devote yourself to saving other Jews from the devastation caused by a lack of Torah observance. Likewise, there is no greater way to honor the Torah than to teach another Jew that the Torah is G-d’s wisdom and will, its lessons and instructions are eternally relevant, and that G-d “sows life within us”—even physical life of this world—through our study of the Torah and our fulfillment of its commands.

—Igros Kodesh vol. 1, p. 164