Kol HaDar B'Chutz La-Aretz...

The Rabbis taught: One should always live in Eretz Yisroel, even in a city that is predominantly idolators, and should not live in Chu"l, even in a city that is mostly Jews, for whoever lives in Eretz Yisroel, it is like he has a God, and whoever lives in Chu"l, it is like he has no God, as it says (Vayikra 25), "to give to you the land of K'na'an, to be to you as a God".
But is it true that one who does not live in the land has no God? Rather, it tells you that whoever lives (dar) in Chu"l, it is as if he is worshipping idolatry, and similarly by David it says (Shmuel I 26:20), "for they have chased me away today from being attached to the inheritance of HaShem, saying, 'Go worship idolatry'". But who said to David, "Go worship idolatry"? Rather, it tells you that whoever lives in Chu"l, it is as if he worshipped idolatry. (Kesubos 110b)

A very strongly worded sugya (like many of the sugyos in Shas dealing with living in Eretz Yisroel are). Rashi on the relevant passuk in Shmuel mentions a similar point, with a couple of interesting differences: "Whoever goes out from Eretz Yisroel to Chu"l during the z'man habayis, it is as if he is worshipping idolatry. Firstly, Rashi does not merely condemn one who lives outside of Eretz Yisroel, but even one who merely goes outside of it - perhaps Rashi was driven to this by the fact that the compulsion of Sha'ul's pursuit would not necessarily have forced David to dwell outside of Eretz Yisroel, in the sense of being settled down, as he could have lived the life of a wanderer (this would depend on the mashma'us of the word dar, whether it implies a permanent dwelling, or whether it can even refer to a sojourner, like the word gar). Secondly, Rashi adds in a caveat not alluded to in the gemara, that this restriction only applies during the z'man ha-bayis. This caveat would seem to not be literal, as during this time period, not only was there no Beis HaMikdash, but the Mishkan was not even in its temporary resting place of Shiloh; rather, it was in the short-term stopover city of Giv'on. The two differences might enable us to reconcile Rashi's opinion with that of the b'raissa, in that they mention two different halachos for two different time periods. Nonetheless, what is Rashi's basis for adding in this caveat?

This previous question was the main point of this post, but as a side point, the first half of the b'raissa is also curious. The first part of the b'raissa said that one who lives in Chu"l is like one who has no God, which is a harsh statement, yet one implied by a passuk. Nonetheless, the gemara rejects this statement, witout providing a reason, and emends the latter part of it to refer to an idol-worshipper, rather than one who has no God. What is the difference between the two categories?

Apparently, it is possible for one who worships idols to have a God. It seems that this can be through one of two interpretations: 1) He has a personal God who watched over him - in this sense, the gemara emends a terrifying situation of one living a quasi-Godless existence, invoked by his residence in Chu"l, to refer instead to the gravity of his sin - although one who lives in Chu"l is a sinner, he's "only" as bad as an idol-worshipper, but still merits "having" a God. 2) He believes in God. An example of the difference between the two cases would be the generation of Eliyahu, in which the people "sat on the fence" between HaShem and Ba'al. The gemara rejects the implication of the passuk that one who lives outside of Eretz Yisroel has no connection to God whatsoever, instead positing that he's merely like an idol-worshipper, who's a terrible sinner, yet still believes in God.

A further point of note is that the gemara, in its question, does not attack the statement that he is "like" one who has no God, but rather challenges the idea that he actually has no God, without the use of the comparative preposition, which is not what the b'raissa itself said. Perhaps the gemara does not attribute any significance to the word "similar", feeling that it was only inserted into the statement to avoid saying straight-out that one who lives in Chu"l has no God, either because living in Chu"l excises oneself from hashgacha p'ratis or because it demonstrates a clear disbelief in God.