"But the people of Israel broke faith in regard to the
devoted things, for Achan the son of Carmi, son of Zabdi, son of Zerah, of the
tribe of Judah, took some of the devoted things. And the anger of the LORD
burned against the people of Israel."
If we look at the book of Joshua we find a striking answer. Sin has a global nature that affects others. Achan sinned by taking things that God had commanded to be given to himself. Achan looked, lusted, stole, and hid these items. Because of what Achan did, the whole nation of Israel was held responsible. 36 men died in the next battle, the nation lost confidence, and the name of the LORD was tarnished.
And God held the whole nation in contempt. He made it clear that when one sinned, all sinned. This is the concept that Paul introduces in Romans. One man sinned, Adam, but the One who died for all, Jesus, takes away the punishment of the sins of all.
Achan sinned, breaking the covenant with God. He dies, his family dies, and only after his death is the covenant restored. We see the global impact of one man's sin. Because of Achan the whole nation of Israel was held responsible. This is incredibly important for us to understand because we think that what we do does not affect anyone around us. This is not true. When I sin, I affect my wife. When I sin, I can affect my future. When we sin, we always hurt others in some way.
We should always take the time to look at who we are and who we are influencing. Our sin affects the people around us. Always.