What is the meaning of "Posechim"?
Radak: This is like a Pise'ach who is lame in both legs. One who is lame in one leg leans on the other leg. One who is lame in both legs does not know on which leg to stand.
Radak citing Targum Yonasan: [Why are you] divided [into two halves? Hashem is Elokim - serve Him alone! Why do you err after Ba'al, which has no power?!]
Malbim: You serve Ba'al, and when evil befalls you, you cry to Hashem, like "uv'Es Ra'asam Yomeru Kumah v'Hoshi'enu" (Yirmeyah 2:27).
What are "Shtei ha'Se'ifim"?
Rashi: It is two thoughts; you do not understand to decide who is G-d. Radak - it says Shtei (feminine), for it refers to Machashavos (thoughts).
Radak citing Targum Yonasan: Two halves. Refer to 18:21:1:2.
Malbim: They are two ideas; you do not know whom to serve. This cannot be, for there is no middle between these opposites! If Hashem is Elokim, Ba'al has no power; Hashem commanded to destroy and abhor it! If [you think that] Ba'al has power, you have no share in Hashem!
What is the meaning of "v'Im ha'Ba'al"?
Rashi: If the Ba'al is G-d 1 [follow it].
Malbim: If [you think that] Ba'al has power!
Presumably, Eliyahu did not want to explicitly say such a Havah Amina, so he omitted 'Elokim'. (PF)
Why didn't they answer him?
Rashi: They did not know to distinguish [which is G-d]. Radak - they were unsure, but when they heard the test, the said that it is good (verse 24).
QUESTIONS ON RASHI
Rashi writes that that could not decide who is G-d. They leaned after Ba'al (only 7,000 in Yisrael had not bowed to it - 19:18)!
Radak: When they saw that rain was withheld like the word of Eliyahu, Navi Hashem, their hearts leaned to Hashem, just Nevi'ei ha'Ba'al misled them, and said not to abandon Avodas ha'Ba'al, for it will do good to them.
