The idea of Christians being salt and light is an abstract concept young children will have a hard time understanding. While you will need to have many conversations over the years about what Jesus meant in Matthew 5:13-18, you can begin with some fun activities.
First grab a flashlight. Go into a room or closet you can make entirely dark. Talk about how hard it would be to read a book or do anything without just a little light. For very small children, you may even bring a book into the room to read to them, but discover you can’t without the light.
Have your child turn on the flashlight. Discuss what a big difference even a little bit of light can make in a dark space. If you have more than one child, have each of them turn on an additional flashlight and show the power of having a lot of people being the light.
Try to explain the verses about Christians being a light in the world. Don’t worry if they don’t entirely understand the connection now. You can continue having conversations over the years as they become more capable of abstract thought.
Then give your kids a salted and unsalted snack. You may have to experiment to find one where the two taste distinctly different. Ask your kids to explain what they believe the salt added to the taste of the snack.
Pull out two pieces of bread. (Non commercially baked breads work better because they have fewer preservatives.) Have your kids put their unwashed hands all over both pieces. One piece of bread should go into a plastic baggie and be sealed. The other should be sprinkled with a tablespoon of salt and placed in a plastic bag so the salt stays on the bread.
Have your kids watch the bread for several days. Which piece of bread grew mold more slowly? Discuss the Bible verses while explaining that salt is used for flavor, preserving food and even disinfecting things. It had so many uses in Bible times (remember there was no electricity, so salting things could also keep them safer to eat) that salt was even used as money at times!
Spend a lot of time discussing what it means for Christians to be salt and light in the world. What are some practical things they can do to be salt and light in their worlds every day?