Family Fun Night in the Mud!
Play tug of war over a mud pit in your back yard or fill some buckets with mud and have a mud fight. The object of course is to get filthy dirty. (If a mud fight is not an option then do something that allows them to get dirty. You can even make some mud in a bowl and trade off putting mud on each other. This could be done indoor if the weather outside is too cold).
When finished, hose off, and go inside for some milk and cookies. Discuss: What did it feel like to be so dirty? Would you like to be that dirty all the time? What did it feel like to be clean again?
This would be a good time to do the following pure water activity as part of your discussion.
Drink It Up
Take a glass of pure water (preferably bottled water that says "pure" on the label). Talk about what makes the water pure (bad stuff is filtered out so only the good stuff is left). Compare and contrast this with God's purity. God is totally clean and pure; there's nothing bad in Him. He doesn't need to be "filtered."
Next, add something you think is very foul into the water and stir it up. (It's gross, but if you have an animal and could add a bit of its droppings to the water, the result is very effective) Ask, "Would you be willing to drink this nasty, polluted water? Why? Why not?" The tiniest bit of something foul destroys the whole glass of water. The tiniest bit of sin would destroy Gods holiness; He would not be pure. God cannot be in a relationship with someone who has been stained or "made dirty" with sin and remain pure and clean. It is important for us to remember that even what we may consider "just a little sin" still makes our clean heart dirty.
The good news is that God made a way for us to be washed clean and pure so we CAN have a relationship with Him! When you accept Christ as your personal Savior and Lord, He washes your sins away once and for all.
Alternate
For other "hands on" activities, see Bonus Activities for God is Holy.
"No matter how...good we try to be, we cannot expect God to allow us into His heaven when we have sin stains in our lives. If He allowed one sin to mar His pure dwelling place, it would cease to be a holy city."
Bill Bright, Discover God