When the Israelites took Jericho they were told to keep away from the devoted (or accursed) things within the city. These would be things that the people devoted to other gods. Yet Achan acts unfaithfully and takes some of the devoted things. His one act of disobedience brought about God’s anger against all Israel.
A lesson for us today…when we sin others almost always get hurt. Sin has consequences.

In Joshua 7, Joshua prays a prayer similar to one that Moses prayed.

God reminds them that they will not be able to stand against their enemies unless they destroy the sin within the camp. Notice also that when God reveals the guilty party (Achan), He does it publicly.

Joshua pronounces curses on Jericho. The results of that prophecy happened during Ahab’s reign. Hiel laid the foundations at the cost of his firstborn, the gates at the cost of his youngest son, just exactly what Joshua had predicted as found in 1 Kings 16:34.

IKing 16:34
In Ahab's time, Hiel of Bethel rebuilt Jericho. He laid its foundations at the cost of his firstborn son Abiram, and he set up its gates at the cost of his youngest son Segub, in accordance with the word of the LORD spoken by Joshua son of Nun.

After Ai was taken Joshua built an altar and read the total Book of the Law, every word to the whole assembly, including women, children, and aliens.

This is great encouragement to read the entire Bible on a regular basis. Just as all of us are doing this year.