We now move away from the first chapters which really focused on the metaphorical use of marriage to depict the prophet married to an unfaithful woman, to pretty much straight prophecy and speaking against the current situation of Israel. Notice the use of Ephraim which is really Israel or the northern kingdom. We do have a divided kingdom where we have Israel or Ephraim or the northern kingdom. We also have Judah which is considered the southern kingdom.
Look at vs.2 where the prophet speaks out strongly against the people by listing 5 of the 10 commandments that they have broken. Look at the list: swearing, lying, murder, stealing, and adultery. That's not completely comprehensive, but not bad in a single sentence. Vs.6 is a powerful verse which tells us: My people are destroyed for lack of knowledge. Ignorance may be bliss, but it is also deadly. Not a good trade-off.