Gemara

(Mishnah): One who hugs or kissing idolatry... transgresses a Lav. One who vows or swears in its name transgresses a Lav.

63a (Rav Dimi citing R. Elazar): One is lashed for all of these, except for vowing or swearing.

Objection: One is not lashed for vowing or swearing, for it is a Lav she'Ein Bo Ma'aseh (without an action). One should not be lashed for the others either, they are Lavim shebi'Chlalos (different Lavim learned from one verse!)

(Ravin citing R. Elazar): One is not lashed for any of these, except for vowing or swearing.

Objection: One is not lashed for the others, for they are bi'Chlalos. One should not be lashed for vowing or swearing, for it is Ein Bo Ma'aseh!

Answer: Ravin's law is according to R. Yehudah, who says that one is lashed for Lav she'Ein Bo Ma'aseh.

(Beraisa): "V'Shem Elohim Acherim Lo Sazkiru" - do not say 'wait for me by idol Plonis.'

Ula (citing R. Yochanan): One may mention any idolatry mentioned in the Torah.

(Rav Nachman): All scoffery is forbidden, except for ridiculing idolatry - "Kara Bel Kores Nevo...Lo Yachlu Malet Masa (the idols could not hold in their excrement) ...u'Chmarav Alav Yagilu Al Kevodo", we read this 'Keveido' (its priests rejoiced that the idols with their feces were taken away).

Rishonim

Rambam (Hilchos Avodah Zarah 5:10): One who vows or swears in the name of idolatry is lashed, for "v'Shem Elohim Acherim Lo Sazkiru." This is whether he swore by (or to) himself, or to a Nochri (some texts - to idolatry). One may not even mention the name of idolatry not in an oath - "Lo Sazkiru."

Hagahos Maimoniyos (3): The Re'em explains that we forbid only a name given for divinity. Names of commoners, e.g. regular names like names of idolatry, even if they made it divine, since this name has no divinity or lordship, and it was not given for this, it is permitted. "V'Shem Elohim Acherim Lo Sazkiru" - the Torah is particular about divine names. Mishnayos teach the names of their festivals - Kalanda, Saturnia, Krastim, for these are commoners' names (even though they are based on the names of idolatry).

Rambam (11): One may not say 'wait for me by idol Plonis,' or similar matters. One may mention any idolatry mentioned in Kisvei ha'Kodesh, e.g. Pe'or, Bel, Nevo, Gad, etc. One may not cause others to vow or swear in the name of idolatry. One is lashed only for vowing or swearing in its name.

Rebuttal (Ra'avad): The Gemara said that one is lashed only according to R. Yehudah, who for a Lav she'Ein Bo Ma'aseh. The Halachah follows R. Yochanan in the name of R. Yosi ha'Glili, that the only Lav she'Ein Bo Ma'aseh for which one is lashed are swearing (falsely in the name of Hash-m) and Temurah.

Kesef Mishneh: Simply, the Gemara connotes like the Ra'avad. We can say that the Rambam holds that both Rav Dimi and Ravin, according to R. Elazar, hold that hugging and kissing are unlike vowing and swearing. They were taught in separate clauses to teach that even though letter of the law there should be no lashes, here there are lashes. We conclude like Ravin that we lash for vowing and swearing, for these are explicit in the verse. No opinion holds that one is lashed for Lav shebi'Chlalos, i.e. there is no reasoning to lash for this. If so, we can say that normally, our Tana does not hold like R. Yehudah. Here he does, due to the stringency of idolatry or for another reason. Perhaps the Tana holds that since one who swears to Hash-m is lashed, even though Ein Bo Ma'aseh, the same applies to swearing in the name of idolatry.

Lechem Mishneh (Hilchos Sanhedrin 19:4 DH ha'Noder): The Rambam obligates lashes when it is done with an action. E.g. he swore to idolatry to eat, and he ate. The Rambam similarly says that 1la for "Al Tifnu El ha'Elilim" only if he transgressed through an action. The Rambam relies on what he wrote elsewhere, that one is not lashed for Lav she'Ein Bo Ma'aseh. The Gemara could have said that R. Elazar's teaching is like Chachamim, and he discusses one who did an action. We said that it is like R. Yehudah, for then one is lashed in every case.

Maharik (Sof Siman 76): The Gemara should have asked simply, one is not lashed for Lavim shebi'Chlalos or Lav she'Ein Bo Ma'aseh. Why did it connect them? (One is not lashed for vowing, for Ein Bo Ma'aseh. One should not be lashed for the others, they are Lavim shebi'Chlalos!) Idolatry is severe. One who admits to it is like one who denied the entire Torah. We thought that due to this, a Lav of idolatry, even if it is shebi'Chlalos or Ein Bo Ma'aseh, is no worse than a standard Lav with an action, for which 1la. (The Gemara asked, we see that this is not (totally) so. R. Elazar holds that one part is true. A Lav of idolatry, even if it is bi'Chlalos or it has no action, is no worse than a standard Lav. Rav Dimi and Ravina argue about which part is true.) The Mishnah forced the Rambam to explain this way. It taught vowing or swearing in a separate clause, to teach that they are different (1la for Lavim in one clause, but not for Lavim in the other clause.) The Rambam did not say that R. Yehudah says so, but the Halachah does not follow him, for a Stam Mishnah says so.

Rebuttal (Gra YD 147:1): This is wrong. The Lechem Mishneh says that he is lashed when Yesh Bo Ma'aseh. In Sanhedrin we asked Stam, which connotes that it applies in every case.

Rosh (7:3): The Gemara connotes that we forbid only cases like 'wait for me by idol Plonis,' in which he mentions it for a need. However, it seems that it is forbidden in every case, for the verse forbids Stam. The Gemara merely gives a typical case, in which he mentions it for a need, and teaches that even this is forbidden.

Poskim

Shulchan Aruch (YD 147:1): One who vows or swears in the name of idolatry is lashed. One may not mention its name, whether for a need or not.

Beis Yosef (DH v'Asur): The Tur forbids mentioning its name needlessly. He means, and all the more so it is Asur for a need. He should have said even needlessly! The Rosh held that it is more obvious to forbid for a need than needlessly, i.e. because the Beraisa teaches cases of for a need, and one might have thought that only this is forbidden. For one who does not know the Beraisa, for a need is no more obvious than needlessly. The Tur should have explicitly taught both of them.

Taz (1): The Tur forbids mentioning its name Chinam (for naught), without need. There are two elements of Chidush. Do not say that we forbid only vowing. Rather, even mere mention is Asur. Also, don't say that it is only for a need. Rather, it is even needlessly. The verse (it seems that this should say 'Tana' - PF) merely taught a common case. Or, one might have thought oppositely, that we are not stringent when there is a need, for all know that he mentions it for a Siman (where to meet). The Tur holds that it is more obvious when it is for a need, for it looks like he gives importance to it.

Shulchan Aruch (2): There is no concern to mention names of their festivals that are like names of people. This is if he does not mention them the way idolaters do, prestigiously.

Gra (3): Oso ha'Ish (their Messi'ah) and his Talmidim are mentioned several places in the Gemara.

Shulchan Aruch (4): One may mention any idolatry mentioned in Kisvei ha'Kodesh, e.g. Kora, Bel, Kores, Nevo, ha'Orchim l'Gad Shulchan.

Shulchan Aruch (5): One may scoff about idols.

Rema: One may tell an idolater 'your god should help you or prosper you.'

Levush (5): This is because one may mock idolatry.

Rebuttal (Taz 2 and Bach DH Kosav): One may not say so! The Nochri does not consider this mockery. The Yisrael encourages his idolatry! Darchei Moshe (1) brings this from his mistaken text of Perush ha'Mishnayos (Gitin Sof Perek 5). The Mishnah permits encouraging Nochrim working in Shemitah! The correct text of Perush ha'Mishnayos permits saying 'Elokim (not Elohecha) should help you.'