The Ramban helps us understand this pasuk by explaining that the heart is comprised of the yetzer tov and yetzer hara, and the “circumcision” is the removal of the yetzer hara, therefore purifying the heart, just as removing the foreskin elevates the baby. He later explains that the “new heart” referred to in Yechezkel is the new heart that will exist in the new reality, in which there is no real desire or choice, rather man will naturally only do according to Hashem’s will.

 The Ramban prefaces his explanation with a passage from the Gemara – whoever comes to be purified, is helped (Shabbat 104). This passage explains to us, that Hashem is anticipating us to return, and the moment our heart is sincere and pure upon returning, Hashem will gather us from the “end of the skies,” and help us complete our return, ultimately by circumsizing our hearts. What we can infer from this, is that in actuality, it’s up to us to get the process started.

Interestingly enough, the word “sky” is mentioned an additional time in this week’s parsha, and also teaches us about the initiative we need to take to get closer to Hashem. “לא בשמים היא” Moshe informs us, that we not need to reach to far to learn the Torah and get closer to Hashem. Especially if Hashem is ready to help us once we initiate. What Rashi explains, however, delivers a powerful message about our responsibility to initiate. Rashi teaches, based on the Gemara in Eruvin, that even if the Torah was in the heavens, we would need to go up and learn it.

Hashem is awaiting our return, and will be willing to gather us from the ends of the sky, if we would desire sincerely to return. It is upon us, however, that even if Hashem will help us, we must understand our obligation to ascend to the sky to Him as well.