Catholic Doctrine Bible Study Session 189: Joshua 1-7 “Catholic ‘Just War’ Doctrine” and “An Individual’s Sin Affects The Whole Community.”
Chapter 2-Rahab, a prostitute, paved the way for the Israelite conquest of Jericho. She is also an ancestor of Jesus! (See Mt. 1:5) God can use anybody!
Chapters 3-6 God provided the victory, because the Israelites cooperated with God. They followed the Ark of the Covenant (prefiguring Mary in the New Testament), and in 6:20 the walls collapsed.
6:21 This was massacre! The Catholic Church forbids it, per a well-thought-out (and inspired by the Holy Spirit!) doctrine on war, spelled out in CCC paragraphs 2307-2317, especially paragraph 2309. (The “Just War Doctrine.”) The Church “loosed” Joshua 6:24, and other Old Testament passages like it, through the power given it in Mt. 16:17-20.
Chapter 7 Achan’s sin (keeping Jericho treasure, against the Lord’s command of 6:18) caused the Israelite defeat at Ai.
Our own “personal” sin affects the community of Christ as a whole; slowly, almost imperceptively, our standards as a community erode, as what once brought shame on the individual is now thought to be “not so bad”, and becomes accepted by the community at large. In that sense, there is no such thing as a purely “personal” sin. We are to be LIGHT to the world!