So now we come to the topic of Achan. Yes, the title of this post is a correctly copied verse from 1Chronicles, and I'm surprised this typo was not noted in the SAB, as Bible critics love to point out scribal errors, which this might be, although it could also be a matter of several hundred years' difference in Hebrew dialect. It is notable that achar is the Hebrew word for "trouble", and the names Achan and Achor that are found in this passage are forms of the word.
The first thing noted in this chapter is that the Israelite leaders rip their clothes, fall face down on the ground and put dust on their heads. This is noted as being absurd and intolerant, and I don't know why it was marked with either. This sort of behavior may seem strange to modern readers, but it was common practice in those days, and in fact may still be among modern Orthodox Jews, though I am not sure about that. It's just a way to show extreme sorrow. As for intolerance, I'm stumped as to what that's supposed to mean
Unless it's referring not to the actions of Joshua and the elders, but to the situation they find themselves in that causes them to be upset. God allowed them to suffer their first defeat at the city of Ai because (as it turns out) one person had done something wrong. As I said in my previous post, whatever this "accursed thing" was that Achan stole is not specifically named (unless it's the garment and precious metal mentioned in verse 21, which is possible if not likely), but the language used to describe it indicates that whatever it was, it was something of some pagan significance that he had no right to have in his possession. Why is it such a big deal?
The Apostle Paul said "A little leaven leaveneth the whole lump," a saying similar to the modern "One bad apple ruins the whole bunch." This is the point of the extremes of Holy war. The people and culture of Jericho had to be completely destroyed, and Achan saving some item he'd taken from the city was simply not acceptable.
In fact, shocking as it seems, it was apparently so very unacceptable that Achan along with his family and possessions were stoned to death and then burned. It's my personal opinion that God decided to have Achan punished so particularly severely in order to make him an object lesson for the rest of the nation. Just as the very first battle they fought in Canaan was won in a particularly spectacular manner to impress upon the people that God was with them in power, so the first transgression was punished in a spectacular manner to impress upon the people that while God was with them, He wasn't going to allow moral compromise.
As for the question of who Achan's father was, that's a simple matter that I've touched on before with other individuals, but I'll repeat here since it's so simple. The word "grandfather" never appears in the Bible. It was customary, whether by culture or by linguistic necessity, for any male ancestor to be called the "father" of a person. Twice in the chapter, Achan is referred to as "Achan, the son of Carmi, the son of Zabdi, the son of Zerah, of the tribe of Judah". While he is once referred to as the "son of Zerah", this labeling is customary despite the fact that Zerah was actually his great-grandfather (or great-great-great-etc., sometimes genealogies are telescoped).