Milah opens the body to soul's light

במד' ואחר עורי נקפו זאת כו' הרבה גרים באו אלולי שמלתי מהיכן הי' הקב"ה נגלה עלי.

In the Midrash: "And after my skin is destroyed, this…" — many converts came because of my milah; for were it not for my milah, from where would HaKadosh Baruch Hu have revealed Himself to me?

Avraham reflects that the revelation he merited, and the converts drawn to him, all flowed from his bris milah — the act that opened him to a higher disclosure of Hashem.

אף שכ' מקודם ג"כ וירא ה' אל אברם.

Even though it had already been written earlier, "And Hashem appeared to Avram."

The Sefas Emes raises a difficulty: Hashem had already "appeared" to Avraham before the milah, so what new revelation did the milah add?

אבל ההפרש שמקודם לא הי' מתגלה לבחי' הגוף רק אל הנשמה ואחר המילה כ' וירא אליו ממש ומקודם כתיב אל אברם כו' השם של האדם הוא כח נשמתו ושרשו.

But the difference is that beforehand it was not revealed to the dimension of the body, only to the neshamah; whereas after the milah it is written "and He appeared to him" literally. And beforehand it is written "to Avram" — for a person's name is the power of his neshamah and his root.

Before milah the revelation reached only Avraham's soul (his "name," his spiritual root). After milah the light reached even his physical body — "He appeared to him," to the whole man.

והנה קודם חטא אדה"ר הי' הגוף מאיר כמו הנשמה.

Now, before the sin of Adam HaRishon, the body shone like the neshamah.

Originally the body itself radiated holiness, fully transparent to the soul's light, with no opacity between them.

ואח"כ כתיב ויעש להם כתנות עור והוא מלבוש הגוף החומריי.

And afterward it is written, "And He made for them garments of skin" — this is the clothing of the material body.

After the sin, the "garments of skin" represent the body's new coarse, physical covering that conceals the soul's light.

אך בני ישראל זכו למצות מילה והוא פתיחת פתח באור זה.

But Bnei Yisrael merited the mitzvah of milah, which is the opening of an entrance within this light.

Milah reopens a passage through that opaque covering, letting the soul's light shine into the body once more.

להאיר הארת הנשמה בהגוף.

To shine the illumination of the neshamah into the body.

The purpose of that opening is precisely to let the neshamah's radiance penetrate and illuminate the physical body.

לכן נקרא ברית כי ודאי מקום פתיחת פתח הנ"ל הוא שרש התקשרות הגוף בכח שרשו.

Therefore it is called bris (a covenant/bond), for surely the place of this opening is the root of the body's attachment to the power of its source.

It is named "bris" — a bond — because this is the very point where the body reconnects to its spiritual root.

ולכן שם נפתח.

And therefore it is opened there.

That specific place is where the channel between body and soul is reopened.

וזהו נק' פתח האהל.

And this is what is called "the entrance of the tent."

The verse's "entrance of the tent" alludes to this opened doorway through which the soul's light now enters the body.

ולכן אחר עורי נקפו זאת שנתגלה הארה גם בגופו ועי"ז יש התדבקות גם לגרים.

And therefore "after my skin is destroyed, this" — for illumination was now revealed even in his body, and through this there is attachment even for the converts.

Once the light penetrated Avraham's very body ("skin"), his holiness became outwardly radiant — and that is why even outsiders, the converts, could attach themselves to him.

ואמנם צריך האדם לתקן ע"י פתח הגוף הנ"ל. את כל חומר גופו ובודאי כן הי' באברהם שגם מקודם תיקן כל גופו רק שהי' נחסר לו פתח הנ"ל וכיון שנימול נמצא שלם בכל השלימות.

And indeed a person must rectify, by means of this opening of the body, all the materiality of his body; and surely so it was with Avraham, who had already refined his entire body beforehand — only this opening was lacking to him, and once he was circumcised he was found complete in all perfection.

The opening of milah is meant to be used: through it one refines the whole physical body. Avraham had already perfected his body; he lacked only this final "opening," and the bris completed him entirely.

ולכן כתיב וירא אליו דהיינו שניתקן כל קומת רמ"ח איבריו והוא יושב פתח האהל שלא סר זכרון הברית מאבינו אברהם אף אחר תיקון כל גופו כתיב יושב פתח האהל:

Therefore it is written "and He appeared to him" — meaning that the whole stature of his 248 limbs was rectified; and "he sat at the entrance of the tent," for the remembrance of the bris never departed from our father Avraham — even after the rectification of his entire body it is written "he sits at the entrance of the tent."

The full revelation came because all 248 of his limbs were now refined. And "sitting at the entrance" shows that Avraham never moved on from the bris: even fully perfected, he stayed rooted at that opening, keeping the bond with Hashem ever before him.

Summary: Bris milah opens a passage in the coarse "garment of skin" that the sin of Adam laid over the body, allowing the neshamah's light to shine into the physical body itself. This is why, after the milah, Hashem "appeared to him" literally — Avraham's whole being radiated holiness, drawing even converts near, and he forever remained rooted at that opened doorway of the covenant.