וַיִּגַּ֨שׁ אֵלִיָּ֜הוּ אֶל־כָּל־הָעָ֗ם וַיֹּ֙אמֶר֙ עַד־מָתַ֞י אַתֶּ֣ם פֹּסְחִים֮ עַל־שְׁתֵּ֣י הַסְּעִפִּים֒ אִם־יְהוָ֤ה הָֽאֱלֹהִים֙ לְכ֣וּ אַחֲרָ֔יו וְאִם־הַבַּ֖עַל לְכ֣וּ אַחֲרָ֑יו וְלֹֽא־עָנ֥וּ הָעָ֛ם אֹת֖וֹ דָּבָֽר׃
Da trat Elija vor das ganze Volk und sprach: Wie lange noch wollt ihr hüpfen auf die beiden Zweige [wollt ihr schwanken]? Ist der Herr euer Gott, so dienet ihm, und wenn der Baal [euer Gott it], so dienet ihm. Aber [das Volk] erwiderte ihm kein Wort.
Rashi
Two concepts. Two thoughts, because you do not know how to decide who is God.
Malbim
Until when Meaning to say how long will you worship Baal and when things are going bad call out to Hashem in the manner of what is written, "in the time of your evil they will say rise and save us", because you swerve between two ideas and do not know who you worship and this is impossible since there is no middle ground. If Hashem is God there is no substance to Baal [who Hashem commanded us] to cut down and consider disgusting. And if there's no substance to Baal you have no part in Hashem. And they did not answer because the people were satisfied as they were.
Rashi
And the people did not answer him a word. Because they did not know how to distinguish [between the two].3After being unable to find Eliyahu in Eretz Yisroel, Achov sent messengers to other kingdoms and nations to search for him. He made them swear that they are unable to find him.—Radak.