Thomas A Rowe has an excellent piece called The Analogy of Faith, dealing with how we interpret scripture. Since some of my readers are in the habit of pulling one passage out of context for their beliefs, I thought I would share this to shed some light on the subject.
The analogy of faith is not the principle that Scripture interprets Scripture, but that all Scripture is in agreement and will not contradict itself. It assumes the unity and harmony of teaching throughout the Bible. In other words, when multiple passages say something about a topic (either explicitly or implicitly), then what those passages say about that topic will be consistent and will not be contradictory. For example, Psalm34:15 speaks of God having eyes and ears, whereas John4:24 says God is spirit. The analogy of faith means that these passages are not contradictory, as they might appear at first glance. We can reconcile them when we recognize that in Psalm34:15 the author is using a figure of speech and is not asserting that God has literal, physical eyes and ears. He is asserting, rather, that God watches over His people and hears their cries for help; whereas in John4:24 Jesus is asserting that God is not a physical being, therefore, the physical location of His worshipers is not what is most important to Him. The analogy of faith forces us to dig further to understand how passages that appear to be contradictory should be understood.
This brings us to another aspect of the analogy of faith, that is, that we should interpret unclear passages in light of clear passages, not the other way around. Milton Terry says the expression analogy of faith “denotes that general harmony of fundamental doctrine which pervades the entire Scriptures.…No single statement or obscure passage of one book can be allowed to set aside a doctrine which is clearly established by many passages. The obscure texts must be interpreted in the light of those which are plain and positive.”2 When a particular passage is unclear to us, we can and should go to other passages that address the same topic more clearly in order to help us understand the unclear passage.