When advocating for correct Biblical doctrine there will always be that one person who responds, “We are not saved by pure doctrine. You are a doctrinal Pharisee advocating for a salvation by works.” This refutation brings up a very valid point. Does doctrine matter and if it does, how much doctrine must be pure if one is to remain a Christian?
Dr. Robert Kolb in his book The Christian Faith presents an excellent metaphor that helps us understand the serious threat that incorrect doctrine has upon Christian thought. His metaphor of the human body also allows us to understand that even though incorrect theology is destructive, it does not necessarily result in one becoming apostate. Finally, his metaphor assists us in understanding that the question, “How much doctrine must be pure if one is to remain a Christian,” is simply the wrong kind of question to ask. He states,
Some people define biblical teaching as a series of topics. Like pearls on a string, these topics are all roughly of equal importance for them. If we conceive of doctrine in this way, we could say that losing any one pearl has about the same effect on the whole of biblical teaching as losing any other pearl. Some people could say that you dare not lose any pearl if you are to be dressed for the host of the heavenly banquet. Others could say that as long as you have a pearl or two left on the string, you are ready to be received at his table.
Others conceive of biblical teaching as a wheel, with a hub and spokes and rim. They suggest that wheels cannot exist without hub and rim and some spokes, but other spokes may be broken without immobilizing the wheel.
Neither of these metaphors adequately describes the nature of biblical teaching. It is better to compare the doctrine of the Scripture to a human body. The body of doctrine cannot exist if Christ the head is decapitated. It dies without the heart of our understanding of how we become right with God pumping away—although the heart, the doctrine of justification, may be partially diseased and still pump, it is true. This was evident in the medieval church, where preachers put a high but false premium on good works and still pointed people to Christ’s saving blood. We see this in contemporary Christians who empathize the contribution of our own personal decision in coming to Christ and still try to cultivate trust in his grace.
If an arm, the doctrine of Baptism, for example, is severed, the body may be able to survive. But it may hemorrhage and die. If the leg of the doctrine of the church become paralyzed, the body may survive, but it will be crippled at best, and it may fall down in a heap and crack the head, too.
So the question, “How much doctrine must be pure if one is to remain a Christian?” is simply a wrong kind of question. The whole of our conveying of biblical teaching needs to be accurate and on target—both because believers need to know what God wants us to know and because God’s Word is true. Nonetheless, sinful doctrinal error does not always break our relationship with the Lord even though it makes it more tenuous.
Applying this metaphor to a contemporary example we can derive that one who embraces the tenets of the Church Growth Movement should not automatically be considered an unconverted pagan outside the Christian faith, but rather a person who walks with a serious limp due to their doctrine of the church (i.e., leg) being influenced by inflated anthropological assumptions. Consider another example, a person who embraces decision theology from the old Semi-Pelagian American Revivals of the nineteenth-century is not necessarily one who is completely lost, but one who tragically has heart disease (i.e., heart of justification is infected with free will theology). Thus, these examples are not necessarily people who specifically reject Christ as the head or promote decapitation. These examples are not necessarily people who reject Justification or celebrate heart disease. Rather, they are individuals whose body of doctrine is unknowingly ill in some areas and possibly healthy in other areas. They are individuals who are at risk of a heart attack and traumatic head injury. They are at risk of losing justification due to their free will theology infecting the heart. They are at risk of the doctrine of Christ being traumatically struck due to their faulty anthropological assumptions weakening the leg; a leg that may give out causing the whole body of doctrine to fall.
Furthermore, this metaphor also helps in showing the motives of those advocating for pure doctrine. Otherwise stated, those advocating for pure doctrine are not advocating for works righteousness by doctrine, but are fighting against false theologies that damn, distort, and poison a person’s body of doctrine. They are not advocating pure theology to meet a certain doctrinal purity quota for a salvific payout, but rather are promoting purity of doctrinal truths for the health of God’s saints.
Finally, this metaphor helps us understand why correct theology matters. It matters because it is indeed important to guard Christ and the doctrine of Justification. It matters because it is indeed important to take note of false theology within secondary doctrines that can advertently and inadvertently impact the head (i.e., Christ) and heart (i.e., Justification).
As a closing point, this metaphor allows us to consider this subject within a compassionate pastoral framework, a framework that causes one to assess a person’s error in light of its seriousness and location in the body of doctrine, which then allows one to assess the proportional corrective response that is needed.
 Robert Kolb, The Christian Faith: A Lutheran Exposition (St. Louis, MO: Concordia Publishing House, 1993), 13-14.