What is the Torah coming to prohibit?
Rashi #1, Rashbam and Ramban #1: The Torah is prohibitting the offering of Korbanos to Hashem in any location 1 other than in the one that Hashem designated. 2
Rashi #2 and Ramban #2 (both citing Makos, 22a and the Sifri 3 ) and Targum Yonasan: It is prohibitting destroying the Name of Hashem 4 - by erasing it from a Seifer, or by removing a stone from the Mizbe'ach (from the Heichal - Sifri) or from the Azarah. 5
Rashi #3 and Ramban #3 (both citing R. Yishmael): It is prohibitting emulating the behavior of the Cana'anim, thereby causing the Beis-Hamikdash to be destroyed. 6
Makos, 22a: Based on the juxtaposition to "ve'Ashereihem Tisr'fun ba'Eish", the Torah is sentencing someone who cooks with the wood of Hekdesh to Malkos. 7
With reference to Pasuk 2.
Ramban: This is a Mitzvas Asei (in Pasuk 5) to give Kavod to Hashem in this way, following the Lo Sa'aseh not to desecrate it. Refer to 12:4:1:2.
See Ramban DH 've'Leshon Sifri'.
With reference to Pasuk 3.
See Torah Temimah citing the Sifri and note 18, who explains why this is not a La'av she'bi'Kelalos. See also Ba'al ha'Turim.
Rashi: R. Yishmael maintains that it is inconceivable for a Jew to erase Hashem's Name or to remove a stone from the Mizbe'ach or from the Azarah. See also Ramban DH 've'Leshon Sifri'.
See Torah Temimah, note 17, who asks that he is Chayav anyway for benefiting from the wood of Hekdesh.
Why does the Torh insert the (otherwise superfluous) words "mi'Kol Shivteichem"?
Rashi: Refer to 12:14:1:1.
