One thing that people forget is that children have concrete thinking. The ability to have abstract thinking does not come until teens. When you say God is in your heart, she is thinking literally, God is in her heart...how can it be that big a man can fit in there? So talking about concepts is hard for little ones. I would focus on: God loves you, like mommy and daddy love you. God watches out for everyone in the world. God is kind and gentle like Mr. X down the street. Give concrete examples...related to life events. Then later on the whole story..whatever you want to teach, can be brought up and added to slowly.