Clarification (Part 1): Rabeinu Tam explains that its real name was 'Kilus' - a Lashon of praise, only the Chachamim nicknamed it derogatively 'Kulis', as in the Pasuk in Tehilim "a mockery and scorn (La'ag va'Keles) ... ".

Clarification (Part 2): And the prefix 'Mar' means 'in place of'' (like we find in Chulin 'be'Mar di'Shechutah', in Bava Kama 'be'Mar de'Parz'la' and in bechoros 'be'Mar de'Kanta'). In other words 'Mar Kulis' means that 'Kulis' is in place of 'Kilus', which they changed.

Clarification (Part 1): And to worship it by means of degrading it ...

Clarification (Part 2): Because if he intended merely to despise it, he would not be Chayav, seeing as according to Rava even me'Ahavah and mi'Yir'ah, he would be Patur; and even Abaye, who declares me'Ahavah and mi'Yir'ah Chayav, would concede here that he is Patur.

Implied Question: Even though the Tana mentions Avodah-Zarah as well as Pe'or and Markulis

Answer: One cannot compare them, since there the Tana comes to discuss their respective Dinim. Here on the other hand, the Gemara is extrapolating from the Reisha, which states 'Eilu Hein ha'Niskalin, Oveid Avodah-Zarah and ha'Nosen mi'Zar'o mi'Zar'o la'Molech', whilst omitting Pe'or and Markulis.

Question: Why is he not Chayav already from his first baby?

Answer: The Gemara is speaking either about someone who only has one son, or who sacrificed all his children simultaneously.

Explanation #1: Two Kerisus in Kedoshim by Molech, Rashi explains, and the third in 'Sh'lach-L'cha - "Ki D'var Hash-m Bazah".

Question: This poses a Kashya on Rebbi, who at the beginning of 'Mi she'Hayah Tamei' establishes "Ki D'var Hash-m Bazah" with regard to 'Porek Ol' and 'Megaleh Panim ba'Torah';` So from where will he learn Kareis by 'Avodah-Zarah she'Lo ke'Darkah'?

Explanation #2: We learn the third Kareis from the Pasuk in Acharei-Mos, which incorporates Molech in the Parshah of Arayos), since "Ki Kol Asher Ya'aseh mi'Kol ha'To'evos ha'Eil ... ve'Nichr'sah" pertains to all the cases mentioned there (including Molech).

Implied Question: Would it not have been more appropriate to establish it with regard to Molech itself , where he passed his child through the fire she'Lo ke'Darkah?

Answer: We prefer to establish it by Avodah-Zarah with 'Im Eino Inyan', seeing as currently we consider Molech no more than a custom, but not an Avodah-Zarah, in which case it wouls not be logical to render it Chayav by She'Lo ke'Darkah.

Question: Seeing as Molech is currently considered an Avodah-Zarah, why can we not learn this from the same Pasuk as we learn Avodah-Zarah she'Lo ke'Darkah?

Answer: We would not have established that Pasuk (which is written by Molech as we explained earlier) by Avodah-Zarah, if we had not found another Pasuk by Molech itself.

Clarification: R. Yishmael is not addressing R. Akiva, who establishes it by Mevarech es Hash-m, but rather to explain his own view, as Rashi explains.

Question: Why can we not pose the same Kashya on R. Akiva, since Kareis in this world we already know from the Pesukim that are written by Molech, which we apply to Avodah-Zarah (Maharshal).

Answer: It may well be that R. Akiva does Darshen the Pasuk "Ki D'var Hash-m Bazah" with regard to Avodah-Zarah at all, but like we Darshen in the first Perek of Shevu'os.

Question: The Kashya however, does pertain to R. Yishmael, who Darshens in Cheilek that "Ki D'var Hash-m Bazah" refers to despising the first Dibur that was said at Sinai - which is Avodah-Zarah. One can now ask on him "Are there three worlds, since Kareis by Avodah-Zarah we learn from Molech?

Answer #1: R. Yishmael however, Darshens two of the Pesukim of Molech with regard to Avodah-Zarah she'Lo ke'Darkah, one regarding this world, and the other, regarding Olam ha'Ba.

Answer #2: Alternatively, one with regard to Avodah-Zarah she'Lo ke'Darkah, and two with regard to Molech, one regarding this world, and the other, regarding Olam ha'Ba.