The infallible rule of interpretation of Scripture is the Scripture itself; and therefore when there is a question about the true and full sense of any Scripture (which is not manifold, but one), it must be searched by other places that speak more clearly.
The Analogy of Scripture
One of the most intriguing and, ironically, the most forgotten paragraphs in the Second London Confession is 1.9. It’s as easy to grasp as it is to say—the Word of God interprets theWord of God. Why is this so simple, yet profound? The bedrock of this orthodox Christian conviction is the doctrine of the inspiration is true, that is, if the Holy Spirit has spoken through the Scriptures, then the chief authority as it concerns what the Spirit has said is the Spirit Himself.
The Bible is unique from any other “holy” book. It took approximately 1,500 years and about 40 different authors for the Scriptures to come together as we have them today. Not only this, but it becomes more clear about its chief end—Jesus Christ our Lord—as it goes. Beginning with only the seed of a woman in Genesis 3:15, it ends with the conquering Lord and Savior coming on the clouds to judge the world and glorify His Church in Revelation.
Since God has determined to reveal His redemptive plan in such a way, by Himself through means of men, the Bible must be interpreted by His people accordingly. Insofar as we follow this infallible rule, our interpretation will be iron-clad.
A Text in Question
Sometimes, Scriptural texts seem difficult to understand. To remedy this, one only need look at the text as a whole. Consider cross references which discuss the same themes, concepts, persons, events, etc. For example, in Genesis 2 we learn Adam is in covenant agreement with God. If he kept the terms of the covenant, he would’ve lived; but he broke the terms and fell. By this act, sin entered the world. Paul lucidly explains in Romans 5 that Adam was a public person, or federal head, through whom sin came to everyone. To know everything God has told us about Adam, we can’t limit our research to Genesis in the Old Testament alone, but must consult Paul in the New Testament as well. In this way, various texts which seem more obscure to us are clarified by other parts of Scripture.
One Full Sense
With the Reformation came the resurgence of the literal meaning of the text. Many of the Medieval theologians had become carried away with allegorizing the text in a way that wouldn’t be warranted by the text itself. The Reformers argued that any sense, whether that be the allegorical, tropological, or anagogical must arise from the assumption of the one literal meaning, or sense. In other words, there may be other senses which arise out of the literal, and in this way a literal truth is revealed by way of allegory, yet there is only one literal meaning. If we were to say there are two literal senses we would have to affirm subjectivism or relativism, and our interpretations would reduce to absurdity.
How do the manifold senses relate?
This is a good question. The on literal sense gives rise to the other senses. For example, David is a type of Christ and in that way, narratives such as David and Goliath are both an historical event and a pointing forward to Christ and His victory over sin, death, and the devil. Here, there are two meanings: a historical event that really happened and a future event that this historical event typologically reveals.
Clear Texts to Less Clear Texts
Earlier, I alluded to the practice of interpreting less clear texts, we’ll call them cloudy texts, with clearer ones. For an example of this, we can go back to our Adamic and Pauline comparison. We see, in Romans 5, that Paul adds further detail, and therefore significance, to who Adam was as he relates to the broader redemptive narrative.
Other texts are like this as well. Allow for one more example before we close. In James 2:17 it says, “Even so faith, if it has no works, is dead, being by itself.” This has led some to think Paul and James are in conflict since Paul says, “For we maintain that a man is justified by faith apart from works of the Law (Rom. 3:28).” These texts will continue to confuse us, and perhaps cause us to come to the wrong conclusions, unless we consider the Bible more broadly. For instance, Paul says in his letter to the Romans, “Do we then overthrow the law by this faith? By no means! On the contrary, we uphold the law (Rom. 3:31),” and:
Now to him who is able to strengthen you according to my gospel and the preaching of Jesus Christ, according to the revelation of the mystery that was kept secret for long ages but has now been disclosed and through the prophetic writings has been made known to all nations, according to the command of the eternal God, to bring about the obedience of faith.. (Rom. 16:25, 26).
So, we see that James and Paul are not in conflict on this point. Both believe obedience or works have something to do with faith. But we see this only because we base our conclusion on more than just two verses which seem to apparently contradict one another. We take the Scripture as a whole, since the only infallible interpreter of the Scriptures is the Holy Spirit.
 Second London Baptist Confession of Faith, 1689. 1.9,