This is one of the most commonly quoted verses in the Old Testament, but rarely is it quoted in full. This is not referring to general knowledge; people are not destroyed due to ignorance of book learning. Rather, people were destroyed through a lack of knowledge of God’s Law (v. 6). If a nation forsakes the Law of God, it has no knowledge of sin (see Rom. 7:7).
Those who have no knowledge of sin cannot repent (how can they, if they don’t know what sin is?); and if they don’t repent, the Bible warns that they will perish (Luke 13:3).
Hosea 4:6 My people are destroyed for lack of knowledge. Because you have rejected knowledge, I also will reject you from being priest for Me; Because you have forgotten the law of your God, I also will forget your children.