Israel had a different understanding of community than we do here in America. When God told Joshua, "Israel has sinned," we in America would rise up to shout: "NO! Achan sinned." We would stew over the 36 soldiers who died at Ai because God found disobedience in Israel. Wasn't that unfair to them?
But Israel did understand, for the Hebrews knew the idea of unity better than we do. They rose and fell as one. When one sinned, they all sinned. When one was punished, they were all punished. When one was honored, they were all honored.
This corporate identity is foreign to those of us raised on cultural independence. But it's important as we follow Jesus. Paul in his letter to the Roman church explained that sin entered the world through one man, Adam. (See Romans 5)
We understand that to mean that we are all infected with the same sin nature because of Adam's sin. But, if sin came to us through one man, then redemption also came to us through one man.
If we're all free agents and lone rangers, then Jesus' work on the cross wouldn't apply to us. We may treasure independence and rights, but we need to set that aside to understand God's work for us.
Consequently, just as the result of one trespass was condemnation for all men, so also the result of one act of righteousness was justification that brings life for all men. (Romans 5:18)