Scripture is…a book for the mission, a portable library of trustworthy samples of gospel speech. Whatever the church in its ongoing encounters with new questions, challenges, and cultures elects to say in its attempt to announce the gospel, such attempts must be tested by the records contained in the New Testament. Moreover, those records are themselves missionary documents: in media res, they offer neither a blank slate upon which to construct the gospel nor a final word definitively closing this or that matter. They are experiments in improvisation on the way from Pentecost to parousia. Gentiles are coming to faith, women are prophesying with heads uncovered, ex-pagans are eating idol meat, traveling teachers are suggesting Jesus didn’t come in the flesh, scoffers are claiming Jesus isn’t coming back, others are saying he’s already returned, Jewish apostles aren’t eating with gentile believers, a church member is sleeping with his stepmother: what to do? These aren’t perennial issues in philosophy, and the apostolic writings are not treatises in systematic theology. They are makeshift answers, sometimes on the fly, to pressing questions of lived faith. That haphazard character may be a thorn in the flesh of theologians, but it is a boon to the church’s life among the nations. For what it offers is not timeless answers but snapshots of the apostles in action, a model for discernment of the Spirit in real time. And when further questions arise—Should we worship Jesus? Is Mary God’s mother? May icons be venerated? Is the Spirit fully God?—the church turns to Scripture not only for divine instruction but for exemplary patterns of sound judgment exercised on the mission field and captured, in the moment, for future generations of believers.