You shall not copy the practices of the land of Egypt where you dwelt, or of the land of Canaan to which I am taking you; nor shall you follow their laws.
אין הולכין בחוקות עובדי כוכבים ולא מתדמין להם, לא במלבוש ולא בשיער וכיוצא בהן, שנאמר ולא תלכו בחוקות העובדי כוכבים, ונאמר בחוקותיהם לא תלכו, ונאמר השמר לך פן תנקש אחריהם. לא ילבוש מלבוש המיוחד להם ... דאסור לישראל להתדמות להם, אפילו ברצועות המנעל ... ומזה ילמוד כל אדם לפי מקומו ושעתו, שהמלבוש העשוי ליוהרא ופריצות, לא יעשה הישראל כן, אלא מלבושיו יהיו עשויין בענין המורה על הכנעה וצניעות,... שדברים הללו דברי שחץ וגאוה הם, ולא כאלה חלק יעקב, אלא דרכם להיות צנועים וענוים, ולא לפנות אל רהבים. וכן כל דבר שנהגו למנהג ולחוק, דאיכא למיחש שיש בו שמץ עבודת כוכבים, לא יעשה ישראל כן. וכן לא יגלח ולא יגדל שערות ראשו כמו הם, אלא יהא מובדל מהם, במלבושיו, ובדיבורו ובשאר מעשיו, כמו שהוא מובדל מהם במדעו ובדעותיו. וכן הוא אומר ואבדיל אתכם מן העמים.
We do not act in the ways of the nations, and we do not emulate them--not in dress, nor in hair style, and the like--as it says, "And ye shall not walk in the customs of the nation" (Leviticus 20:23). And as it says, "Neither shall ye walk in their statutes" (Leviticus 18:3). And as it says, "Take heed to thyself that thou be not ensnared to follow them" (Deuteronomy 12:30). ... And from this every person should learn, according to his time and place, that the clothing that is made for arrogance and licentiousness--a Jew may not use it. Rather, his dress must be made in a way that is instructive of submissiveness and modesty. For these are matters of arrogance, and this is not the portion of Jacob. Rather, their [the children of Jacob] way is to be modest and humble, and not to turn toward conceit. And so too anything which they [the nations] do that can be suspected of containing an iota of foreign worship, a Jew may not do it. And so he may not shave his head or grown his hair like them. Rather, he must separate himself from them in dress and speech and in all his other actions, just as he separates himself from them in his knowledge and opinions. And so it is said, "And I have set you apart from the peoples" (Leviticus 20:26).
תוספות על עבודה זרה י"א: אי חוקה היא היכי שרפינן. תשריפה לאו חוקה היא והתם משמע דחוקה היא לכ"ע והוה אסירא אי לאו טעמא דכיון דכתיב וכו' לכך פירש ר"י דתרי גווני חוקה הוו אחד שעושין לשם חוק לעבודת כוכבים ואחד שעושין לשם דעת הבל ושטות שלהם והכא בשמעתין מיירי באותו חק שעושים לשם עבודת כוכבים וה"פ ר"מ סבר שריפה לאו חוקה היא לעבודת כוכבים להכי פריך ואי חוקה לעבודת כוכבים אנן היכי שרפינן והא כתיב ובחוקותיהם לא תלכו ואע"ג דכתיבא באורייתא יש לאסור כיון שלהם הוא חק לעבודת כוכבים דומיא דמצבה כשהיו מקריבין עליה אבות היתה אהובה לפניו משעשאוה האמוריים חק לעבודת כוכבים שנאה והזהיר עליה דכתיב (דברים טז) לא תקים לך מצבה ומסיק אלא דכ"ע לאו חוק היא לשם עבודת כוכבים ומ"מ הוא חק הבל ושטות.
This is why the Ri explains that there are two types of Chukah. One is a chukah that is a rule for idolatry. One is a Chukah that is made for their own silly reasons. Our Gemara is referring to a Chukah that is made for idolatry...The Gemara concludes that according to everyone, this is not a Chukah for idolatry; it is a Chok of silliness. In Sanhedrin (52b), the Gemara understands that Chok is an importance, based on our Gemara’s conclusion. Accordingly, even Rebbi Yehudah agrees that we do not derive from here that this is a forbidden practice if the Torah states this practice, as this is not a Chok for idolatry. If it would not have been stated by the Torah, we certainly would not act in this fashion, even if it was only a silly (and not idolatrous) action... B
הגה: ...וְכֵן שֶׁעוֹשִׂין מִשּׁוּם כָּבוֹד אוֹ טַעַם אַחֵר, מֻתָּר (מהרי''ק שֹׁרֶשׁ פ''ח). לָכֵן אָמְרוּ: שׂוֹרְפִין עַל הַמְּלָכִים וְאֵין בּוֹ מִשּׁוּם דַּרְכֵי הָאֱמוֹרִי (ר''ן פ''ק דַּעֲבוֹדַת כּוֹכָבִים).
Ramah: Similarly, things that are done out of respect or another reason, it is permitted [for one to do such things]. And therefore they said one may burn [the items of deceased] kings, and there is not in this “the ways of the Amorites.”
אורחות צדיקים א':ט
וגם נכרת בעניין מאכל ומשקה, ובמלבושי בגדי גאווה מלבושי נכרי. ועל זה הוזהרנו בתורת משה, שנאמר (ויקרא כ כג): "ולא תלכו בחוקת הגוי"; וכתיב (ויקרא יח ג): "ובחוקותיהם לא תלכו"; ונאמר (דברים יב ל): "השמר לך פן תנקש אחריהם" – הכל בעניין אחד הוא מזהיר, שיהא ישראל מובדל במלבושיו ובדבריו ובכל מנהגיו מן הגויים. וכן הוא אומר (ויקרא כ כו): "ואבדיל אתכם מן העמים"
מתני׳ יוצאין בביצת החרגול ובשן שועל ובמסמר מן הצלוב משום רפואה דברי ר"מ וחכמים אוסרין אף בחול משום דרכי האמורי:
גמ׳ יוצאין בביצת החרגול דעבדי לשיחלא ובשן של שועל דעבדי לשינתא דחייא למאן דניים דמיתא למאן דלא ניים: ובמסמר מן הצלוב: דעבדי לזירפא: משום רפואה דברי רבי מאיר: אביי ורבא דאמרי תרוייהו כל דבר שיש בו משום רפואה אין בו משום דרכי האמורי הא אין בו משום רפואה יש בו משום דרכי האמורי
MISHNA: One may go out on Shabbat with a locust egg, and with a fox tooth, and with a nail from the crucified, for the purpose of healing; this is the statement of Rabbi Meir. The Rabbis prohibit using these remedies even during the week, due to the prohibition of following the ways of the Amorite. These are superstitious beliefs and the customs of gentiles from which one must distance oneself. With regard to the halakha in the mishna, the Gemara cites Abaye and Rava, who both said: Anything that contains an element of healing and seems to be effective does not contain an element of the prohibition against following the ways of the Amorite.
Rav Moshe Feinstein: On the question of celebrating any event on a holiday of Gentiles, if the holiday is based on religious beliefs [by the Gentiles], such celebrations are prohibited if deliberately scheduled on that day; even without intent, it is prohibited because of marit ayin (24) . . . The first day of year for them [January 1](25) and Thanksgiving is not prohibited according to law, but pious people [balai nephesh] should be strict. (Iggerot Moshe, Yoreh Deah 4:11(4)): It is obvious in my opinion, that even in a case where something would be considered a prohibited Gentile custom, if many people do it for reasons unrelated to their religion or law, but rather because it is pleasurable to them, there is no prohibition of imitating Gentile custom. So too, it is clear that t if Gentiles were to make a religious law to eat a particular item that is good to eat, halacha would not prohibit eating that item. So too, any item of pleasure in the world cannot be prohibited merely because Gentiles do so out of religious observance.
i
On the issue of joining with those who think that Thanksgiving is like a holiday to eat a meal: since it is clear that according to their religious law books this day is not mentioned as a religious holiday and that one is not obligated in a meal [according to Gentile religious law] and since this is a day of remembrance to citizens of this country, when they came to reside here either now or earlier, halacha sees no prohibition in celebrating with a meal or with the eating of turkey. One sees similar to this in Kiddushin 66 that Yanai the king made a party after the conquest of kochlet in the desert and they ate vegetables as a remembrance. Nonetheless it is prohibited to establish this as an obligation and religious commandment [mitzvah], and it remains a voluntary celebration now; in this manner -- without the establishment of obligation or religious commandment -- one can celebrate the next year too with a meal. But, I think, nonetheless it is prohibited to establish a fixed day in the year for the celebration and it is only in the first year of the event, like when Yanai conquered, and then they had a party, and not for permanence. There is also a problem of adding commandments .. (27) Even though one can question the source, it is still a real prohibition.i
Shulchan Aruch Safed, Israel, Yosef Karo 1563, Yoreh Deah 178:1
(The most widely accepted compilation of Jewish law ever written)
"One [a Jew] should not follow the customs of non-Jews (nor should one try to resemble them). One should not wear clothing that is particular to them [i.e., their culture]; one should not grow forelocks on one’s head like the forelocks on their heads; one should not shave the sides [of one’s head] and grow one’s hair in the middle of one’s head [like they do]; one should not shave the hair in front of one’s face from ear to ear and let one’s hair grow [in the back] [like they do]; one should not build places [i.e., buildings]—like the non-Jews’ temples—so that large groups of people will enter them, like [non-Jews] do. RAMA: Rather, one [i.e., a Jew] should be distinct from them [i.e., non-Jews] in one’s manner of dress and in all of one’s actions. But all of this [i.e., these restrictions] apply only to things that non-Jews do for the sake of licentiousness. For example, they are accustomed to wearing red clothing, which is official/princely clothing, and other clothing that is similarly immodest. [These restrictions also apply] to things that they are accustomed to doing because of a custom or rule that does not have a[ny underlying] reason, out of concern that [a Jew who does such things will follow the] “ways of the Amorites,” and that it has the blemish of [i.e., is tainted by] idol worship inherited from their ancestors. But things that they are accustomed to doing for a useful purpose—such as their custom for expert doctors to wear particular clothing so that the doctors will be recognized as specialists—one is permitted to wear [such clothing]. Similarly, things that are done out of respect or another reason, it is permitted [for one to do such things]. And therefore they said one may burn [the items of deceased] kings, and there is not in this “the ways of the Amorites.”