What is the meaning of "Niv'ar Kol Adam mi'Da'as"?
Rashi (here and 51:17): Everyone who makes an idol is [foolish,] like "Ish Ba'ar" (Tehilim 92:7) and "Niv'aru ha'Ro'im" (below, verse 21).
Radak: [Was eradicated] every man who acts with Chachmah.
Malbim: All scientists who probe nature are Niv'ar mi'Da'as (withheld from knowing) how Hashem arranged that rain fall in its time according to what the land needs. They tried to explain the nature of each matter; what they could not explain, they attributed to hidden matters and supreme powers. From this, they came to serve idols. When they see Hashem's Chachmah and ability in general, constant matters such as rain, thunder and lightning, they could not know this via investigation.
What is the meaning of "Hovish Kol Tzoref mi'Pasel"?
Radak: Every smelter is ashamed of his image, because it cannot do [anything], and he calls it god!
Malbim: If they will pray to the image for rain, they will know that it is Sheker (futile).
What is "Nisko"?
Rashi: It is an expression of Masechah (a molten image).
Radak: It is covering, like "veha'Masechah ha'Nesuchah" (Yeshayah 25:7) and "Kesos ha'Nasech" (Bamidbar 4:7).
Why does it say "Ki Sheker Nisko"?
Radak: He covered it in gold in vain. It does not help at all, it only fools the people. This is Sheker!
Malbim: There are three Chesronos in idols. (a) It does not answer prayer. Everything that Nevi'ei ha'Ba'al said in its name is Sheker. (b) It does not have even Ru'ach of Chachmah or life. (c) It does not have even special natural powers like some things have, e.g. magnets.
