There are two ways to go after God. If you want to be with God—if you want standing with God, acceptance with God, pleasing God—you can go about it two ways. You can become a slave and work for God, or you can become a child and live enjoyably in his house. A slave tries his best to perform in such a way that he might win a standing with a master. A child rests in the incomparably wonderful truth that his name is in the will that his father wrote before he had a chance to win anything from the father. Slaves are always uncertain. They're never quite sure that they've done enough to please the master. Children don't even think of it that way. They're already in the house.When I first listened to this message, I thought, "Wow, that's great stuff." Then I weighed his words against all the NT language that clearly describes believers as both sons and slaves to God. I wondered whether Piper has set up a false dichotomy.
But within the context of Galatians 4-5, I think this is not only a theologically accurate statement, but also a soteriologically essential one. I think most of us would agree that Paul is not here contradicting other statements about our slave relationship to Christ. Piper seems to be getting to the narrower parameters of Paul's point—not that we are free from responsibility to serve God, but that we are incapable of serving him in such a way that we can earn anything from him. Rather, what we possess in Christ, we possess by grace—by his free, unmerited declaration that we are his sons and his heirs.