These two principles mean that we should read the Bible in light of the gospel and judge every matter by it. Whatever is out of harmony with the gospel, especially as it is expounded in the New Testament Epistles, is to be rejected, even if it comes buttressed with numerous "proof"-texts. It is not sufficient to affirm the Bible is true. Even Jehovah's Witnesses do that. We need to affirm that the gospel is the truth of the Bible. All doctrinal questions should be determined in the light of the gospel.

We say that the New Testament must interpret the Old Testament because the Old Testament is the preliminary and fragmentary revelation. Its institutions are shadows of the reality to come. Its prophecies veiled promises of a salvation not yet revealed. But in the New Testament gospel of Jesus Christ, God's secret is out and His glory is unveiled. Here is God's final word "beyond which there is no more to be seen or experienced." (2)

The apostles did not come to believe the incarnation and the resurrection of Christ by their ingenious exegesis of the Old Testament. Rather, they were confronted with these historical realities. They then read and understood the Old Testament in light of the transcendent Christ event. We should do the same.

We should not build a doctrinal edifice out of Old Testament scriptures nor pour the New Testament gospel into and Old Testament mold. Jesus Christ cannot be contained by Old Testament forms. While He fulfilled the hopes and destiny of Israel, He transformed them. For example, the Old Testament prophecies could only couch God's eschatological salvation in terms of blessings on Palestine, prosperity for Jerusalem and favor to the house of David. All that God promised to Israel was fulfilled when He raised Christ and inaugurated His reign (Acts 13:32-33). But how exceedingly above any literal reading of the prophecies is the glory of His exaltation and the favor showered upon His people! In fulfilling the Old Testament, there, Jesus shattered and broke through the limited forms of Judaism, whether those forms were its legal system or its prophetic vision. The gospel of Jesus Christ was the new wine which could not be contained in the old wineskins of Judaism. In Christ old things passed away and all things became new
(2 Corinthians 5:17).

The coming of Christ transformed the apostles' understanding of the Old Testament. It should transform our understanding of the Old Testament as well. We must not come to the New Testament from the Old, but to the Old Testament from the New.

Not only must the New Testament interpret the Old Testament, but the Epistles must interpret the Gospels. While Jesus was still with the apostles in the flesh, He did not say all that He desired to tell them. He declared: "I have much more to say to you, more than you can now bear. But when He, the Spirit of truth, come, He will guide you into all truth" (John 16:12-13)

After the Spirit was poured out at Pentecost, the New Testament Epistles systematically explained the meaning Christ's death and resurrection. Some of Christ's sayings recorded in the Gospels remain rather enigmatic. Without the clarifying light of the Epistles, they could be misunderstood. Luther's opponents, for example, thought they found "proof"-texts for justification by works in the teachings of Christ.

On the issue of Sabbatarianism, the final court of appeal must be the New Testament Epistles. We should be suspicious of any major doctrinal assertions not clearly supported by the New Testament Epistles.

Footnotes

(Unless otherwise noted, Scripture quotations are from the New International Version.)

(1) In his book, The Case for Orthodox Theology, Edward J. Carnal lists five rules for biblical interpretation. His first two rules are mentioned here.

(2) Ernst Kasemann, Commentary on Romans, p. 10.