We read in Joshua about Achan's sin, holding back some of the spoils of the victory at Ai, and as a result, Israel fails in their next battle because it displeases God so much. So, what was the severe offence that Achan committed that would cause God to be willing to let his people suffer defeat? Well, if we go back to Deuteronomy, and we see in Deuteronomy 13, we see the idolatrous city among Israel in the future, if they follow after other gods, they are to be offered as a burnt offering. And the word for holy war, cherem, is used there. So, what holy war is, or what cherem warfare is, is a war that is not for the enrichment of the victors as is common state war, but holy war is a type of final judgment that prefigures the final judgment of God in the new heavens and earth wherein those who are not holy and right before God are totally consumed as burnt offerings to him. And so, when Achan held back from the spoils of the battle, he was actually holding back something that belonged to God. He was stealing from God to enrich himself, which is the exact opposite of righteousness. The righteous man gives to God and trusts God to provide for, sustain and support him. Now, what is remarkable about the Achan episode is that it's repeated in a manner in the book of Acts with Ananias and Sapphira. Scholars have noticed a number of parallels between Achan's sin and what Ananias and Sapphira did, which tells us this, that a lack of generosity, not being generous to God's purposes in the Christian community, is tantamount to the kind of thing that Achan did back in the book of Joshua.