The answer is: Achan

Josh 7:1 - Achan's sin was the cause of the defeat at Ai resulting in 36 Israelites being killed in the battle.

Achan’s story in the Book of Joshua serves as a gripping reminder of the consequences of individual actions on the community. Picture this: after the monumental victory at Jericho, in which the walls crumbled and the people shouted in jubilation, Achan, driven by greed, decided to pocket a few treasures that were devoted to God — a blatant disregard of the divine command. The irony is that this single act of disobedience not only brought tragedy into Achan’s life but also led to the crushing defeat at Ai, where his fellow Israelites lost their lives. Talk about an "ooops" moment!

Did you know that Achan's actions led to intense introspection and communal learning? The narratives surrounding Achan are unique in that they emphasize both accountability and the communal consequences of personal sin. Joshua learned that God’s presence among his people was conditional upon their faithfulness — a principle that recurs throughout the Bible. Also, biblically speaking, this episode echoes themes found in Genesis with the story of Adam and Eve, showcasing how one person's disobedience has repercussions that ripple out to affect many.

Yet in a twist, when Achan was discovered, he confessed and faced the consequences, illustrating a notion that resonates throughout scripture: acknowledgment of wrongdoing, however heavy the price, is a vital step to restoration. Just like Achan's story warps in mystery and tension, it challenges readers to think about the impact of both loyalty and betrayal in our own lives.