In this thirty-second essay in the series “Is Christianity True?” I want to deal with a common objection to Christian belief. It goes something like this: Let us grant that the arguments made so far in this series show that it is not irrational to believe in Jesus’ resurrection and all that follows from it. Let’s even grant that the series has made a good case for Christian faith. Still, the evidence is not so overwhelming that it makes nonbelief irrational; there may be plausible alternative ways to account for the same set of facts even if we can’t think of one. In other words, the objective evidence for the truth of Christianity does not amount to proof and, therefore, cannot reasonably be translated into subjective certainty. But the decision to become a Christian is so radical, so comprehensive, so demanding, and so life changing that no one can do this without subjective certainty. But such subjective certainty goes beyond where the evidence can take you. And common sense tells us we should proportion the level of belief to the strength of evidence.

What can we say to this objection, which I will label the “proportionality objection”? Consider how the proportionality objection treats the judgment about Christianity’s truth and the decision about becoming a Christian. It assumes that the type of judgments made in mathematics and logic are ideal and ought to be the standard against which every judgment is measured. These sciences possess such clarity in their terms and lucidity in their operations that they can claim certainty for their conclusions and complete confidence for actions based on them. Other rational endeavors fall short. The type of evidence used in history, metaphysics, and theology does not possess the clarity and lucidity of mathematics and hence cannot lead to the level of certainty attained in mathematics. Perhaps so. But does it follow that to be rational we must proportion belief to evidence and hence hold back from the radical, comprehensive, demanding, and life changing decision to become a Christian? I do not believe so.

In investing in stocks, it makes sense to diversify. If you have $100,000 to invest, you would be wise not invest all of it in stock from one company. In this case it makes sense to proportion your belief and action to the evidence. But in other areas it is impossible to divide your loyalty and action. Some things are either/or, yes/no, or on/off. You do them or you don’t. You do one or the other, but not both. You can’t marry someone 98%. You can’t dive into the pool 75%. You can’t be a little bit pregnant. Some actions require 100% decisiveness even if the evidence provides us with only 98% confidence. When it comes to action we must take risks. Becoming a Christian is an action like getting married or diving off a diving board. You can’t be 50% Christian. Hence contrary to the proportionality objection voiced above, proportioning one’s Christian commitment to the evidence would not be a rational action. It would be an irrational one, since it attempts to do the impossible. It is not reasonable to apply rules taken from one area (mathematics or investing) and apply them thoughtlessly to a different area.

On a practical level, when you try to proportion belief in Christianity to the strength of the evidence supporting it, you don’t become somewhat Christian or a little bit Christian; you simply don’t become a Christian at all. The proportionality objection applied to Christianity in effect advises that since you cannot be 100% certain that Christianity is true, you must treat it as 100% false. And it does this because it fails to understand the difference between belief and action. A person may believe strongly or weakly or not at all that there are nonhuman intelligent beings living somewhere in our universe. As long as such an idea is proposed as a mere belief, something one might discuss as a curiosity or an interesting problem, it makes sense for us to place ourselves on a quantitative scale from 0 to 100% belief. But as soon as there is a call to action, we find ourselves faced with an either/or decision.  Christianity issues a call to action, and it does not allow for proportionality in our response. It’s all or nothing. And we don’t get not to decide.