There's a lot more to learn. But if we flub that lesson, if we don't know that God loves us, then we have missed the boat. It's why we have the stickers and the songs. It's why we have the Secret Pals. It's why we have the cards, and the hand-painted clay flower pots, and all the other stuff during the year.
Love is the lesson.
We keep on teaching it, year after year, because it is the most important lesson any of us will ever learn. We pick our teachers, not just because they're knowledgeable, but because they love children. We want teachers who will model, in a way that can be seen, the love and concern that God has, the love of God that we want them to learn more about as they grow up. If love is the general description of what we are trying to teach, then story is the specific content. We want people to know, in vivid detail, the stories of people who have tried to live in faith with God.