In 2 Kings Chapters 15, we find a summary of 7 different kings - 2 rule in Judah and 5 in Israel. As you read, you see a continual spiral downward and their worst enemies were within their very own kingdoms. In Chapter 16, Ahaz rules in Judah and behaves pretty much like a pagan northern king. If these kings were to shoot at the right target, they'd aim straight for God. Instead, they continually follow their own plans, leave the trader gate open by not getting rid of all the pagan shrines, and end up in a continuous downward spiral.
