Hosea was a prophet of Israel during the reign of Jeroboam. See more about the context of what's being said in Hosea 4:6 in
1 Kings 12, and in
Hosea 1.
As others here have pointed out to you, Hosea 4:6 is addressed to Israel at the time it was written.
"My people are destroyed for lack of knowledge,.... This is not to be understood of those who are the Lord's people by special grace; for they cannot be destroyed, at least with everlasting destruction; God's love to them, his choice of them, covenant with them, the redemption of them by Christ, and the grace of God in them, secure them from such destruction: nor can they perish through want of knowledge; for though they are by nature as ignorant as others, yet it is the determinate will of God to bring them to the knowledge of the truth, in order to salvation; and that same decree which fixes salvation as the end, secures the belief of the truth as the means; and the covenant of grace provides for their knowledge of spiritual things, as well as other spiritual blessings; in consequence of which their minds are enlightened by the Spirit of wisdom and understanding, and they have the knowledge of God and Christ given them, which is life eternal. But this is to he understood of the people of the ten tribes of Israel, who were nationally and nominally the people of God, were so by profession; they called themselves the people of God; and though they were idolaters, yet they professed to worship God in their idols; and as yet God's "loammi" had not taken place upon them; he still sent his prophets among them, to reprove and reform them, and they were not as yet finally rejected by him, and cast out of their land. These may be said to be "destroyed", because they were threatened with destruction, and it was near at hand, they were just upon the brink of it; and because of the certainty of it, and this "through the lack of knowledge": either in the people, who were ignorant of God, his mind, and will, and worship, and without fear and reverence of him, which was the cause of all the abominations they ran into, for which they were threatened with ruin; or in the priests, whose business it was to teach and instruct the people; but instead of teaching them true doctrine, and the true, manner of worship, taught them false doctrine, and led them into superstition and idolatry; and so they perished through the default of the priests in performing their office; which sense is confirmed by what follows:"
Source (
Gill's Exposition of the Entire Bible).