Reductionism is the concept of taking a biblical doctrine and reducing, summarizing or ‘boiling the doctrine down’ to one finite statement that could very well be an oversimplification.  Worse than that reductionism may be ignoring the entire counsel of the Word of God in favor of one passage.  One premium example of this would be the polarized views of Calvinism or Armenianism.  Both of these views (when taken to their logical extreme) can be examples of reductionism.  The scriptures put a great amount of tension on the subject of God’s undeniable sovereignty and man’s undeniable responsibility for sin and other actions.  Are these two different ideas mutually exclusive?  No.  The scriptures present a paradox wherein God is sovereign and man is responsible for his actions.  This isn’t inconsistency, its the complication of mankind being created in God’s image and therefore having a will and God’s being God and not having any of His power lessened by man’s ability to desire and will various things.

Reductionism is what fans the flames of fanaticism or doctrinal narrowness in areas where the scripture presents a message that is more broad.  Baptism’s relationship to salvation is a good example of people reducing all theology down to a few passages even though other passages in no way require water baptism.  Or furthermore the idea that tongues is a heavenly prayer language… their is only one text that could be gone to for proof text and that is not what the context of the passage that I Corinthians 13 is referring to.  Reductionism is what allows bad theology to stay bad and what keeps believers blind.

When you study a doctrine make sure that you review what the whole word of God says about that doctrine and in the correct context.