Shared ground
Joshua closes his farewell by tying two claims together: Israel has already seen God keep every “good” promise, and that same reliability means God will also carry out the threatened “harmful outcomes” if Israel breaks the covenant (textual claims: none of the good promises failed; as good came, so harm will come; disobedience includes serving other gods).
The passage treats the land as a gift already received (“this good land…has given you”) and treats continued life in the land as conditional on covenant loyalty. The main covenant breach named is turning to other gods in worship (“serve…bow down”).
Joshua’s approaching death (“the way of all the earth”) functions as a solemn frame, but the argument rests on Israel’s lived history: they “know…in all [their] hearts and…souls” that God’s word has proven dependable.
Where interpretation differs
Some readers take “destroyed…from off this good land” and “perish quickly” to mean total annihilation of the people. Others read the language as primarily about being removed from the land (loss of place, security, and national life there), not the end of Israel’s existence.
There is also some discussion about what “evil things” means here. Many take it as “harmful events” (disaster, defeat, exile) rather than God doing moral evil, since the contrast is between good outcomes and harmful outcomes.
Why the disagreement exists
The key terms can sound absolute (“destroyed,” “perish”), but they are paired with a specific location (“from off the good land”), which can point toward expulsion. Also, “quickly” can be read as immediate in Joshua’s horizon or as a warning about the decisiveness of the outcome once covenant breaking reaches a tipping point, even if the later history unfolds over time.
What this passage clearly contributes
This ending reinforces a central theme in Joshua: God’s promises have been reliable in Israel’s experience (compare the book’s emphasis on not one promise failing, e.g., Joshua 21:45). The passage also states plainly that covenant relationship includes consequences in both directions: blessing is not random, and judgment is not arbitrary. Finally, it names idolatry—serving and bowing to other gods—as a concrete, covenant-breaking act that leads to losing the land that was given as a gift.