There are two aspects to this question that are quite distinct. The first, objective version of the question asks whether Christian beliefs are true and able to be supported with evidence, such that a person could justifiably hold those beliefs on rational grounds. This is the question usually addressed by Christian apologetics. Some of my own attempts to answer such questions may be found here and here on this weblog and here and here on my parish website.
The second version of the question pushes aside the answers to the first and zeroes in on a perceived irrationality in Christian faith as it is actually held by the vast majority of adherents. In other words, it questions the rationality of the subjective act of believing itself rather than the objective content of what is believed. It is with this aspect I am concerned here.
Indeed, it is assumed by atheists that the two aspects are fundamentally disconnected, in that, it is argued, whatever purported rational justifications of generally theistic or specifically Christian beliefs are put forward by believers, they are not the true reason these people believe but ex post facto rationalisations. Atheists contend that Christians consider it virtuous to believe things without any rational justification, so that their apologetics are intellectually inconsistent at best and insincere at worst. Catholics in particular reply by pointing out that in fact theologians have taught that we are only obliged to have faith in the teachings of the Bible and Church as divine truth once we are firmly persuaded that God exists and that he has revealed himself and his will through the Bible and Church, and that this judgement can be based on rational consideration of the evidence. In other words, Catholic Faith is not required to be “blind”.
However, the atheist can plausibly respond: “Yes, that may be true in theory, or even in practice for a small minority such as yourself or some Thomists, but the overwhelming reality is believers who glory in believing without reason and have never considered the approach you outline necessary.” Now, it is true that few Christians are explicitly Thomist and that few rely on “proofs” of God’s existence or the Bible’s/Church’s divine inspiration/guidance to argue themselves toward intellectual faith in Divine Revelation. Does it follow that, whatever theologians may do or think, the vast majority of Christians practise a faith against or in spite of reason? No, but this will not become obvious until we investigate the various ways humans know what they know and the relationship between Christian faith and other forms of knowledge.
In discussions of epistemology, of what humans can know and how they know it, it is common to distinguish between certainty and certitude. Certainty is the quality of that which is true and can be known to be so by a properly functioning, sufficiently informed intellect. Certitude is the disposition of the mind towards a proposition that it thinks is certain, whether or not the thing is in fact true or certain. In this discussion I will be using the words “knowing” or “knowledge” to mean “thinking something is true with moral certitude, that is, being sure enough to stake one’s overall well-being or other matters of importance on it”. In other words, I will be including in such knowing that which is held with certitude, whether or not it possesses certainty as well, so that it may or may not be defeasible knowledge. We can then go on to ask what types of human knowing are reasonable or not by asking whether or not those types of knowing are trustworthy, that is, if they can and do match subjective certitude with objective certainty. Finally, we can, based on this criterion, say whether Christian faith is rational and why.
We are, then, at present primarily interested in whether the subjective act of faith is the result of a mind working in accord with reason and honest perception, such that any true knowledge obtained is not obtained merely accidentally but due to a proper functioning of that mind. Remember, the atheist claim is not just that theism and Christianity are wrong, but that believers accept them as right for no good reason or no reason at all and call that acceptance “having faith”. Thus, it is asserted, faith is irrational and unwarranted.
The key to understanding why faith does involve a proper functioning of the mind is to start by looking at all the main human means of knowing and how reliable they are.
How do humans know things? Let’s make a list based on common-sense and experience:
1. Axioms and mathematical relationships may be called tautological (true by definition), “basic” or even self-evident. E.g., “2 + 2 = 4” and “All effects are the result of causes.”
2. Direct sensation or experience. E.g., “That car is red.”
3. Inference by deduction. Syllogistic reasoning. E.g., “All humans are mammals. I am a human. Therefore, I am a mammal.”
4. Inference by induction. Or, “trial and error”, “Does it work? Try it and see.” In other words, knowledge through verification of predictions and repetition with success. If a theory keeps its “promises” when practised, we trust it. E.g., “The Sun will rise in the East tomorrow.”
5. Authority. E.g., “I’ve never seen directly that the Earth goes around the Sun and I don’t understand the proofs it does, but all the scientists tell me it does, and that’s good enough for me.”
6. Intuition. This can be considered a kind of integration of elements of 1 to 5 operating in an implicit or subconscious manner. E.g., “I don’t know how to explain it, but I just knew how to throw the ball so it went over that barrier but under that roof.” “I knew there was something awry with that mathematical proof and the accompanying diagram, but couldn’t see what it was exactly till later.”
The above 6 modes of knowing are roughly in order of decreasing assurance, though the order can be different for different people in different areas. For example, for a man with poor vision, mode 2 may be inferior to mode 5 when making a judgement about shapes or colours, especially if the authority relied on is the consensus of many neighbouring observers. Nevertheless, reliance on these allows for true knowledge of many things most of the time, and is able to match certitude and certainty when the modes work together to give the same “answer”. And much of our true knowledge relies on modes 4 to 6 rather than 1 to 3. For example, our judgements of the personal trustworthiness of friends and thus the truth of what they say rely on intuition and induction from experience, followed by accepting something on their authority.
Now, the modes of knowing associated with coming to or retaining faith are the very same ones. However, different believers will have different epistemological emphases. There are basically 3 ways of becoming or remaining a Christian. First, one might be brought up as one from childhood, accepting what your parents taught you (5). But then it is unlikely true faith will remain unless the faith is practised and works (4)! That is, it keeps its promises and leads to experiencing or “apprehending” God (2*). Second, there are those who convert after childhood, who can be divided into two groups. The first come to Christ with less argument or explicit reasoning and more intuition (6) and emotional response to the Gospel, trusting those who bring them that Gospel (5), but still come to know and experience God (2*). Third, there are those who logically deduce the truth of Christianity (3) either through a more intellectual journey via the arguments of apologetics based on cosmological and historical arguments (1, 2 & 5) or through experience of a miracle (2). These also lead to the spiritual contact with God to which I have already referred (2*). Finally, all these believers come to accept the divine (and therefore perfect) authority of Christ, the Church & the Bible (5*) as deductions of these processes of inference.
Clearly, the claim that Christians possess faith as an essentially arbitrary or irrational act unrelated to trustworthy mental processes is false, as long as mode 2* — the “clincher” that often turns merely probable knowledge or opinion into moral certitude — is real. But since it is supposed to be a gracious act of God and is, strictly speaking, incommunicable, non-believers can only dismiss it by first dismissing the objective truth of Christianity and theism. Therefore, the attempt to argue Christian believing would be mostly irrational, even if what was believed happened to be true, fails. The only other escape for the atheist who wants to prove Christian believing must be a misuse of the mind (without addressing the objective truth of what is believed) is to show that manifestations of 2* are merely natural epiphenomena of the brain. I have addressed that claim here.
Christians, through the special version of mode 2 that I have marked above with an asterisk, experience God through a new spiritual faculty which is analogous to a new “sense”. However, it is not simply a superadditum. It is a quickening and enlightening of the whole soul and body, including the senses, imagination and reasoning. See 1 Corinthians 2.12ff and Hebrews 6.4, 5. The importance of this factor is that it is necessitated for all who are to be saved by the fact that fallen man cannot have Christian faith without grace healing and empowering nature, according to Scripture. This allows the certitude and certainty which leads to acceptance of the whole Faith on the authority of God (the special version of mode 5 marked with an asterisk above), who will not deceive and certifies his Word to us by his Word within us, so to speak (modes 2* & 5* in synergy).
Therefore, Christian faith results from mental processes compatible with and overlapping (though also exceeding in scope and reliability) normal integrated mental processes that are rational in the sense of being significantly more successful than not in acquiring true beliefs. Also, faith is rational in the sense that, not only is it at least as likely to acquire truth as normal human “knowing”, but it does so through intrinsic epistemological appropriateness rather than simply through serendipity or the interference of divine omnipotence. God does not override our minds and just “turn on our faith-switch”, so to speak. There is no artificial inducement of certitude unrelated to all other mental processes.
It is in this latter assertion that I differ most from Professor Alvin Plantinga’s theory of “proper basicality”. Briefly, he posits that there is a sensus divinitas in all human beings which, ceteris paribus, causes belief in God, and a sensation or direct cognitive recognition of God as Judge and Saviour in believers which causes living, penitent faith in Christ. These cognitive dispositions are put there by God and require no reasoning or external justification to produce certitude. Because they succeed in acquiring truth by God’s sovereign providence and grace, they match certitude with certainty and can be considered “warranted” even though they do not rely on human reason at all. Furthermore, the believer is thus not required to justify his beliefs using other reasons and is justified in saying he knows the truths of the Faith with assurance despite this. That is, his belief is “properly basic” or appropriately held as virtually axiomatic.
Where I differ from Plantinga is that I say the spiritual faculties abovementioned are only analogous to a new or extra “sense”. In fact, these faculties do not necessarily immediately produce belief as if it were axiomatic or self-evident. They cooperate with and include the other human modes of knowing. This is in accordance with the Catholic principle that “grace perfects nature” rather than overriding or destroying it. The sensus divinitas integrates and elevates other knowledge. Too, whereas Platinga seems to distinguish strongly between the two “senses” and grant them both certitude-producing properties, I would say that the belief in God of non-Christians is perhaps not assured faith-knowledge but strongly (and reasonably) held opinion, strictly speaking.
I suspect, contra Plantinga, that there is always some type and degree of inference involved, even if only intuitive and implicit (see mode 6 above), in getting from the spiritual sense of God to actual belief, or at least in preparing the ground for the spiritual sense to do its work by removing obstacles and correctly predisposing the mind. Otherwise the talk in the New Testament of “proofs” of the Resurrection (Acts 1.3) and St Paul’s “reasoning” and “persuading” (Acts 18.4) makes no sense.