When I hear that question it makes me think about what I want to be when I grow up. I have always wanted to be a missionary. I want to tell little kids about how Jesus died on the cross to pay for their own sins. I want them to know there is a hell and there is a heaven. That there is a God and there is a devil, but you should keep in mind Jesus is always with you even when you are doing a horrible thing.
I sometimes go to church, but I know Jesus still loves me even if I don't go to church enough. So remember if a child asks you "Who is God? " "What does he do?", tell them he is a wonderfull person that loves everyone even when they are being bad. Don't be afraid to tell what he did and who he is to everyone, because I am 11-years old and I want to tell everyone who God is!