To teach children about faith you must first teach the kids the definition of faith. For the definition of faith the students will open their Bible to Hebrews 11:1.
Now faith is the assurance of things hoped for and the evidence of things not seen.
So what does that mean? Discuss with the class about things we hope for or believe, but do not see- or see right away. We hope for the sun to come up every morning, the evidence is not there until the next morning comes. We believe that Christopher Columbus discovered America, none of us were there to see it, but we believe it to be true. We cannot see wind, but we see the evidence of it when trees sway or a windmill turns. That is evidence of things not seen.
Unannounced, throw a small ball towards the children. One of them will catch it. Use this as a visual lesson about faith. Tell the kids that you had faith that one of them would catch the ball. There was no proof prior to you throwing the ball, but you trusted it would happen. That is what faith is like- trusting in someone or something to be true.
Do another demonstration of faith by having a child come forward and stand on a chair. Stand behind the student and tell him to fall backwards and that you will catch him. If the child trust you he will have faith that you will catch him. Discuss with the children that it takes faith to believe in God and trust Him to save us.
Look up another verse.
But without faith it is impossible to please God. For whomever comes to God must believe He IS, and He rewards those that diligently seek him.
Do you have faith enough to believe God exist?
Is there any evidence that God exist?
Talk about how our world shows the existence of God. Ask how the world got here, let the kids answer. Surely one will bring up evolution in some form. To refute evolution ask the children if they've ever seen a tall building. How did it get there? We don't believe that buildings, cars or streets just happen or evolve. Someone built them. Why would you believe that something as complex as or earth just happened, doesn't it make more sense to believe God built it. The Earth is evidence of something not seen, God.
God rewards those that seek to know Him. The reward is being saved from our sin and spending eternity, after we die, with Him in Heaven.
Ask the class, "how do you get that reward?"
Use this time to present the Gospel and give an invitation to accept Jesus.