From Fitzpatrick and Thompson's great book, Give Them Grace: "First, you could dangle a carrot in front of the donkey, fooling the donkey into thinking that if he pulls the cart far enough, he’ll get to eat the carrot. The second is to prod the donkey along the road by hitting him with a stick. If the donkey is motivated by the ultimate reward of a carrot, the stick won’t be necessary, but if he’s not really all that interested in carrots, then the stick will be employed. Either way, through reward or through punishment, the cart driver gets what he wants.
Because both parents and children obstinately refuse to pull the cart of God’s glory down the road, the Father broke the stick of punishment on his obedient Son’s back. Rather than trying to entice us by dangling an unattainable carrot of perfect welcome and forgiveness incessantly in front of our faces, God the Father freely feeds the carrot to us, his enemies. He simply moves outside all our categories for reward and punishment, for human motivation, and gives us all the reward and takes upon himself all the punishment. He lavishes grace upon grace on us and bears in his own person all the wrath that we deserve. Then he tells us, in light of all that he’s done, “Obey.” Yes, we do have promises of rewards in heaven, but these are not earned by us through our merit. Yes, there are promises of punishment, but not for those who are “in Christ.” All our punishment has been borne by him.
The carrot is ours.
The stick is his.
Manage [your children] with beans in a jar if you must, but be sure to tell them that it isn’t the gospel. And perhaps, once in a while, just fill the jar up with beans and take everyone out for ice cream, and when your son asks you, “Daddy, why do we get ice cream? How did the jar get to be full?” you’ll know what to say, won’t you?"