Supplies: water, paper towels
Spill some water on a table. Explain to the kids that the water represents sin. The towel represents you. As you fill yourself with more and more sin you become less useful. Eventually the paper towel is so waterlogged that it rips and is destroyed. Sin does the same thing to us. The more we fill our lives with sin the more useless we become to God and eventually sin completely destroys us.