Here are the readings with a few comments to get you started.
Joshua 5:9–12
The manna stopped. What does that mean?
2 Corinthians 5:16–21
What does it mean to be "Christ's ambassadors"?
Luke 15:1–3, 11–32
Help me with a new angle on this parable.
Update: I think I will focus on the passage from 2 Corinthians. I see the theme of reconciliation as the key to connecting with our situation. We tend to emphasize individual reconciliation with God, but I think Paul has much more in mind.