The Descriptive and The Prescriptive
David committed adultery with Bathsheba. Should you? What are the limitations on the use of descriptive passages in establishing doctrine? We know that God condemns worship based on our own ideas of how to approach and appease Him. Consider Aaron's sons: Nadab and Abihu.1 No one could question that they were sincere. No one could question that they wanted to do something for God. Theirs was a harsh lesson between the prescriptive and descriptive. The text about them is not only a description but gives the prescriptive will of God concerning the worship they were supposed to have offered.
Can certain descriptive passages be used to establish doctrine and practice? Yes! Consider the doctrine of the Hypostatic Union of Christ. The various passages that describe Christ as man and as God must be understood as limitations on how we are to understand Christ's Divine-Human nature when the prescriptive texts tell us to worship Him as the One True God.
Can it be that certain prescriptive passages do not establish doctrine and practice? Yes! Consider the commands for the observation of the three high festivals when every circumcised male was to appear at the Temple, or the command to stone rebellious children to death. These are certainly prescriptive passages, but there is more in the Scripture that tells us about how we are to view the ceremonial and civil law since their fulfillment in Christ.
In the end it is the context of the whole of Scripture that shows the interpreter what is to be normative for faith and life. But by nature all Christians want to be pietists and transfer their memberships to the church of Galatia. The opinio legis is our constant companion. Preachers are never to think themselves exempt. As interpreters of God's Word to God's flock it is a constant temptation to try to preach the Third Use of the Law. When we attempt to do so we usurp the work of the Holy Spirit. The Three Uses of the Law are not guidelines on how preachers are to attempt to use the Law of God in interpreting the Scriptures to His flock. The Three Uses of the Law are descriptions of how God the Holy Spirit uses His own Law in working on the hearts of the hearers.
It is this author's opinion that all pastors need to reread four books at least each year: The Bible, The Lutheran Book of Concord; The Hymnary; and Walther's The Proper Distinction Between Law and Gospel. Each interpreter of Scripture should be able state clearly and concisely why these particular four works should be selected out for pastors in particular. These works represent the source and norm of interpretation, the confessional limits and experience of the Church in interpretation, the application of interpretation to the flock in its worship and life, and the proper application of God's Word to the flock during the chief act of interpretation: the sermon.
The frequency of rereading is not meant to be understood as a divine directive to the reader. It is meant to point out the weaknesses of the interpreter and his need for constant refreshing, reeducation, and edification of his own knowledge and skills. Constant immersion in these sources, chiefly the Scriptures, will enable the interpreter to grow in discernment between descriptive and prescriptive passages as well as their proper application to the flock of God.