Christians, whom is this verse referring to in the Bible?

At the time that Isaiah utters this portion of his prophecy, the leaders of Judah do not have faith like that of Hezekiah. They have drunk themselves into a spiritual stupor by means of their alliances with ungodly nations. “Linger, you men, and be amazed; blind yourselves, and be blinded. They have become intoxicated, but not with wine; they have moved unsteadily, but not because of intoxicating liquor.” (Isaiah 29:9) Spiritually drunk, these leaders are unable to discern the import of the vision given to Jehovah’s true prophet. Isaiah states: “Upon you men Jehovah has poured a spirit of deep sleep; and he closes your eyes, the prophets, and he has covered even your heads, the visionaries. And for you men the vision of everything becomes like the words of the book that has been sealed up, which they give to someone knowing the writing, saying: ‘Read this out loud, please,’ and he has to say: ‘I am unable, for it is sealed up’; and the book must be given to someone that does not know writing, somebody saying: ‘Read this out loud, please,’ and he has to say: ‘I do not know writing at all.’”—Isaiah 29:10-12.