Put worship music on in the house and in the car. There are some fabulous worship CDs for children. When our children were young we played The Music Machine, the Poke Dot Bear and so many others. Let the music play in their rooms at night as they are going to bed or if it is more up-tempo, play it during the day and let them dance. There are many CDs and DVDs available for children of all ages. Kids love to see other kids worshipping.
When they are older, take them to a church youth group. Teenagers need to belong. They need to be around other believers their age. Don't be afraid to let them ask questions. God is not afraid of them asking and He is very capable of answering.
Read stories to them that are faith based. We would have dinner together as a family and after dinner Jim would often read a chapter from a faith-based book. Something that we could discuss with them, inspire them and make them think. Or he would read a true story of faith to inspire and stir faith within them. Then we would discuss what God was calling us to do and ask them what they thought. We wanted them to grow up believing they could and would be mighty in God and do great exploits.
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