Our Gemara on Amud Beis discusses the rabbinic enactment that the very earth from outside Israel has an impurity to it. Shem MiShmuel (Ki Savo 9) discusses the mystical peshat in why this is so.

Land itself has a certain drive and magnetic draw. Many cultures refer to their country land as “mother” or “father”.  The Torah itself has references to the land itself, almost like it has a personality. For example (Vayikra 20:22):

וּשְׁמַרְתֶּ֤ם אֶת־כָּל־חֻקֹּתַי֙ וְאֶת־כָּל־מִשְׁפָּטַ֔י וַעֲשִׂיתֶ֖ם אֹתָ֑ם וְלֹא־תָקִ֤יא אֶתְכֶם֙ הָאָ֔רֶץ אֲשֶׁ֨ר אֲנִ֜י מֵבִ֥יא אֶתְכֶ֛ם שָׁ֖מָּה לָשֶׁ֥בֶת בָּֽהּ׃

You shall faithfully observe all My laws and all My regulations, lest the land to which I bring you to settle in spew you out.

Or 

Devarim (19:10):

וְלֹ֤א יִשָּׁפֵךְ֙ דָּ֣ם נָקִ֔י בְּקֶ֣רֶב אַרְצְךָ֔

Thus blood of the innocent will not be shed in your land

Shem MiShmuel explains that Bereishis Rabbah (5:10) says the Hebrew word, “Eretz” is reminiscent of the word “Ratz”, to run. The land of Israel runs to do the will of God.  However, Shem MiShmuel says that is only the nature of Israel; the secular land runs away from God, because, after all, it is earth. The nature of land is to be drawn to something, and whatever fills up that vacuum can be good or evil.  In rabbinic thought, the world is divided that way too, with the Greeks (and by extension, the Romans) representing physical and profane strivings, while the Jewish experience is toward a spiritual striving, each embodied in their homelands.  It is in this context that we can understand Gemara Megilla (6a):

קֵסָרִי וִירוּשָׁלַיִם, אִם יֹאמַר לְךָ אָדָם: חָרְבוּ שְׁתֵּיהֶן — אַל תַּאֲמֵן. יָשְׁבוּ שְׁתֵּיהֶן — אַל תַּאֲמֵן. חָרְבָה קֵסָרִי וְיָשְׁבָה יְרוּשָׁלַיִם, חָרְבָה יְרוּשָׁלַיִם וְיָשְׁבָה קֵסָרִי — תַּאֲמֵן, שֶׁנֶּאֱמַר: ״אִמָּלְאָה הָחֳרָבָה״. אִם מְלֵיאָה זוֹ — חֲרֵבָה זוֹ, אִם מְלֵיאָה זוֹ — חֲרֵבָה זוֹ.

The Sages said that the fortunes of Caesarea, which represents Rome, and Jerusalem are diametric opposites. If, therefore, someone says to you that both cities are destroyed, do not believe him. Similarly, if he says to you that they are both settled in tranquility, do not believe him. If, however, he says to you that Caesarea is destroyed and Jerusalem is settled, or that Jerusalem is destroyed and Caesarea is settled, believe him. As it is stated: “Because Tyre has said against Jerusalem: Aha, the gates of the people have been broken; she is turned to me; I shall be filled with her that is laid waste” (Ezekiel 26:2), and Tyre, like Caesarea, represents Rome. Consequently, the verse indicates that if this city is filled, that one is laid waste, and if that city is filled, this one is laid waste. The two cities cannot coexist.

The impurity of secular lands represents striving that is not channeled in service of closeness to God but instead toward the impure.  The purity of Israel, of course, represents the opposite.

Heading into Chanuka, we must keep in mind that there are two poles that we are inevitably drawn toward, and they are not at peace with each other.  Athens and Jerusalem will never be completely at peace outside of us, nor inside of us.  

However, we should not confuse the struggle as a sign of pathology. To the contrary, the struggle is there because we must exist in both worlds, and cannot be too comfortable.  As it states in Eicha Rabba (2:14)

אִם יֹאמַר לְךָ אָדָם יֵשׁ חָכְמָה בַּגּוֹיִם, תַּאֲמֵן,... יֵשׁ תּוֹרָה בַּגּוֹיִם, אַל תַּאֲמֵן

If a person will say to you: ‘There is wisdom among the nations,’ believe it…[If a person will say:] ‘There is Torah among the nations,’ do not believe it.

It is noteworthy that the rabbis in the Gemara Megilla and Eicha Rabba used the same phrase “believe” “תַּאֲמֵן”.  This suggests that they were discussing the same subject matter.