(ג) משרשי המצוה. מה שכתבנו באזהרת טרפה בסדר משפטים, כי יודע אלקים כי כל המאכלות שהרחיק מעמו אשר בחר, יש בהם נזקים מצויים לגופים שהם כלים לנפשות לפעל בהם ולהתעלות על ידי מעשיהם הטובים. ועל כן הרחיקנו מהם למען יפעלו הנפשות פעלתן ולא ינעלו [דלת] בפניהם רע מזג הגופות וטמטום הלבבות, וכמו שכתבתי שם.
(3) What we wrote in the warning of the 'torn' animal in the Order of Mishpatim (Sefer HaChinukh 73) is from the roots of the commandment - as God knows that all of the foods that he distanced from His people that He chose, have [properties] in them [that] injure bodies, [and] that stop the souls from activating them and elevating them with good deeds. Therefore, He distanced us from them, in order that the souls will make their impact; and that a bad constitution and a blockage of the heart not seal the door in front of them, as I wrote there.
(ט) השאלה הח' למה נאסרו המאכלות האלו שנזכרו בפרש' בבהמה ובעוף ובדגים ובשרצים האם מפני בריאות הגוף וטוב מזגו עינינו הרואות כל האומות האוכלים אותם שמנים ובריאים אין עיף ואין כושל בהם גם יש ב"ח אחרים ארסיים בטבעם שהם יותר מזיקים וממיתים באכילתם שלא הזהיר' תורה על אכילת':
The 8th question is: why does the Torah specifically prohibit these foods mentioned in this section, is it because they are healthier for the body and good? Our eyes see the nations of the world and some are fat and healthy and not tired and noth failing and they are also foods that are worse for you and can kill you and the Torah does not warn us about eating those foods.
Horeb
The more passive and submissive the body is, the more it will yield to the dictates of the soul as man's higher nature.
Midrash Tadshe
He [Adam] may remember his Creator each time he looks at this tree, submit to the divine authority, and beware of pride.
Rabbi Soloveitchik, Festival of Freedom, p. 137
The Torah is of the opinion ... that it is impossible to hallow and inspire the spirit without disciplining the body, [Kashrut laws] belong to the category of discipline of the body and its sanctification. [As a result], what is forbidden here is overindulgence in satisfying human corporeal needs and drives.
איסורי אכילה להבדיל מן העמים. וגם לרומם הנפש שאכילת הדברים המאוסים מביאה פחיתות נפש, ואין הטעם לשמירת הבריאות, כי אמנם בשר הגמל הוא טוב לבריאות, והוא חביב מאד לאנשי המזרח.
The prohibition to eat [certain foods] is to separate [the Jewish people] from the nations and also to uplift the soul because eating disgusting things leads to a lessening of the soul. And, the reason [for kashrut] is not for health reason because camel meat is good for health and is beloved by people of the east.
Rabbi Soloveitchik, Kashrut & Kedusha
We have existed for almost 2,000 years without a sanctuary [Beit HaMikdash], and the absense of its service has not affected the integrity of our people. If a Jewish community would reject kashrut, however, it would become assimilated in a few generations.
(ו) אֵלּוּ דְבָרִים שֶׁל גּוֹיִם אֲסוּרִין וְאֵין אִסּוּרָן אִסּוּר הֲנָאָה. חָלָב שֶׁחֲלָבוֹ גוֹי וְאֵין יִשְׂרָאֵל רוֹאֵהוּ, וְהַפַּת, וְהַשֶּׁמֶן שֶׁלָּהֶן. רַבִּי וּבֵית דִּינוֹ הִתִּירוּ בַשֶּׁמֶן. וּשְׁלָקוֹת, וּכְבָשִׁין שֶׁדַּרְכָּן לָתֵת לְתוֹכָן יַיִן וָחֹמֶץ, וְטָרִית טְרוּפָה, וְצִיר שֶׁאֵין בָּהּ דָּגָה כִלְבִּית שׁוֹטֶטֶת בּוֹ, וְהַחִלָּק, וְקֹרֶט שֶׁל חִלְתִּית, וּמֶלַח סַלְקוֹנְטִית, הֲרֵי אֵלּוּ אֲסוּרִין וְאֵין אִסּוּרָן אִסּוּר הֲנָאָה:
(6) These are the items of non-Jews that are prohibited, yet their prohibition is not against deriving benefit from them: milk that was milked by a non-Jew without a Jew watching, and [their] bread, and their oil [although] Rabbi and his court permitted [their] oil, and stewed vegetables, and pickled vegetables to which it is their custom to add wine and vinegar, and minced fish, and fish-brine that does not have kilbit [a kind of small fish] floating in it, and the chilaq fish, and a [cut] piece of asafoetida, and seasoned salt, all of these [items of non-Jews] are prohibited yet their prohibition is not against deriving any benefit from them.
אתמר מפני מה אסרו שכר של עובדי כוכבים? רמי בר חמא אמר רבי יצחק משום חתנות, רב נחמן אמר משום גילוי.
Because of marrying them - so that you don't get used to making festive meals with gentiles and seek after their daughters.
רב פפא מפיקין ליה לאבבא דחנותא ושתי. רב אחאי מייתו ליה לביתיה ושתי. ותרוייהו משום חתנות.
The Gemara cites the opinions of various Sages with regard to beer. Rav Pappa had them bring out the beer belonging to gentiles from the store to the entrance of the store, and he would drink it outside the store. Rav Aḥai had them bring the beer to his house, and he would drink it there. And both of them drank the beer away from the presence of gentiles due to concern about marriage with gentiles.