by Craig Branch – (Introduction to Areopagus Journal Vo. 6 No. 2, March-April 2006)


There is a scene early on in C.S. Lewis’s novel The Lion, the Witch, and the Wardrobe in which the character Lucy has just returned from her first journey into Narnia and has told her siblings about this magical place.  Peter and Susan come to their guardian, Professor Kirke, concerned about Lucy. The Professor asks, “What were you doing in the Wardrobe?” Peter responds, “You wouldn’t believe us if we told you.”  The Professor responds, “Try me.”  As they skeptically relate Lucy ‘s story, the Professor challenges their assumption that Lucy is making it up.  Susan asks, “Are you saying that we should believe her story?”  He answers, “Why not?”  Susan tells him, “Well, logically it’s impossible!”

“Logic!” said the Professor, “Why don’t they teach logic at these schools?  There are only three possibilities. Either your sister is telling lies, or she is mad, or she is telling the truth. You know she doesn’t tell lies and it’s obvious she is not mad. For the moment then, and unless any further evidence turns up, we must assume that she is telling the truth .” Professor Kirke is encouraging his wards to truly apply the principles of logic to the case at hand-in which case, they would see that it is not illogi­cal to believe Lucy’s tale. C.S. Lewis uses a similar logi­cal “trilemma” in Mere Christianity to argue for the deity of Christ – Jesus, he argued, was either Lord, liar, or lunatic.

This issue of Areopagus Journal is about logic.  When our staff decided to cover this topic, my apologist’s cynicism gave rise to anxiety.  Will our readers even bother to read it?  Or worse, will people not renew their subscriptions? Won’t people perceive it to be too dry, too academic, or even irrelevant?  But continue to read and I believe you will perceive and understand the vital relevance of this topic.


Let’s begin with a few definitions of logic.

Logic may be defined as the science that evaluates arguments.   [An Argument] is a group of statements, one or more of which (the premises) are claimed to provide support for, or reasons to believe a conclusion.1

Logic is the study of the methods and principles used to distinguish good (correct) from bad (incorrect) reasoning . . . .The distinction between correct and incorrect reasoning is the central problem with which logic deals.2

Logic is the study of the methods by which the con­clusion is proved beyond all doubt.  Given the truth of the premises , the conclusion must be true.  In technical language, logic is the science of necessary inference.  From such and such premises the conclu­sion necessarily  follows. 3

Why study logic? The use of and the need for logic is unavoidable and indispensable. One cannot not use it. Logic is a fundamental and necessary component of epistemology (the study of knowing how to know anything truly) .

Thoughts or conclusions usually result in choices and actions. Ideas have consequences for individuals, for relationships, for society and culture. Everyone needs to use basic logical laws to reason clearly and communicate coherently.

If logic is disregarded or even disdained, then the ability to discern truth is lost, and the distinction between right and wrong, good and evil, just and unjust, will also disap­pear.  The rejection of logic means the end of morality.  If one cannot distinguish any of the above categories then there is no basis for morality!

This fact is becoming more and more clear in both Eastern and Western cultures.  Hinduism, Buddhism , Taoism and the various “New Age” cults make the truth claim (which in itself is a contradiction) that reality is non-dualistic- i.e. there  is no  absolute truth’ no ultimate right or wrong, evil or good.  Likewise, the West’s drift into postmodernism posits the similar idea that our fini­tude makes it impossible to say for sure what is true.

Without knowledge and use of logic one could not point out the emptiness and irrationality of statements like, “All truths are half-truths,” “There are no absolute truths ” “All truth’s are relative,” or “To claim you are right is intoler­ant and bigoted.” These statements are as self-refuting as statements about “Square circles,” or sentences like “I can’t speak or write a word of English,” “I only accept statements that are five words or less and no more,” and “All generalizations are false.”

The knowledge of sound logic is necessary for the Christian in two ways.  First, we are commanded to love God with all our hearts, souls, minds and strength (Mark 12:30).  So, the study of logic is not optional because we are called and expected to seek understanding of God’s revealed truth and live in obedience to that truth.

The second necessity for knowledge and the use of logic is to better engage unbelief, both in unregenerate persons and in the cultural systems that are antithetical to God’s truth.  So, logic is a component of apologetics.

Even though God has ordained His elect to be saved  He has also ordained the means by which they are saved. Regeneration and conversion happen at a point in time, but preceding that point there is almost always a process. No one comes to the Father except the Holy Spirit draws him (John 6:44), but that drawing is a process.  The means that God has ordained are various: Christians liv­ing out their faith as a “sweet aroma” (2 Cor. 2:5, Acts 2:44-48), Christians speaking forth the gospel (2 Cor. 5: 17-21; Matt. 28: 18-20), and Christians reasoning, per­suading, and using argumentation in correcting wrong beliefs (2 Tim. 2:23-26; 2 Cor. 5:11; Acts 18:, 19; 19:8;

28:23-24;  17:17-34).

Because we live in a world full of influences that shape the way we think, reason, and act, we need to take much more seriously the need to develop the disciplines to be good Christian thinkers so that we can be an effective part of the processes God has ordained to bring His elect to saving faith.  As J.P. Moreland observes,

Our society has replaced heroes with celebrities, the quest for a well-formed character with the search for a flat stomach, substance and depth with image and personality.  In the political process, the make up man is more important than the speech writer, and we approach the voting booth, not on the basis of a well-developed philosophy of what the state should be, but with a heart full of images, emotions, and slo­gans all packed into 30-second soundbites. 4



In order to help the reader see the practical relevance of a study of logic, let me discuss a specific theological and apologetic issue that a proper understanding of logic can illuminate.  I refer to the doctrine of the trinity.  Christians believe that the self revelation of the triune nature of God is essential to worshipping the one true God as opposed to the myriad of false, man-made gods.

But most cults, false religions, and skeptics deny and attack our belief in the triune nature of God.  Groups like Jehovah ‘s Witnesses, Oneness Pentecostals and Muslims often display an inadequate understanding of this doctrine. And some of them resort to the twisting of Scripture to undermine the biblical teaching on the trinity.  In addition to a thorough understanding of what the Bible teaches about God, we need to be prepared to apply sound princi­ples of logical reasoning to respond to the cultist’s and skeptic’s misuse of logic in attempting to disprove the trinity.

God in His Word reveals that there is only one true God and many false gods.  He reveals that His Being is uniquely triune by nature.  The classic formulation of this doctrine is that God is one being consisting of three dis­tinct Persons, each person sharing one divine substance (homoousios).

At this point come the attacks. “So you’re saying that the Father is one Person and is one in substance. Then you say that the Father, Son, and Holy Spirit are each distinct Persons. Then they must be each distinct substances­ three different gods. Or perhaps you mean that each Person is part of God, so that 1/3+1/3+1/3 =1. Or maybe you are saying 1+1+1= 1-which is irrational. For exam­ple John, David, and Bill are each human persons. John is not David, David is not Bill, and John is not Bill, and they are not one human being, but three.  So, how can God be three Persons, yet one God?  It’s illogical.”

Another attempt to (mis)characterize the trinity as irra­tional goes as follows:

  1. The Father is
  2. The Son is
  3. The Holy Spirit is
  4. The Father is not the Son and the Son is not the Holy Spirit and the Holy Spirit is not the Father.
  5. There is one and only one

According to numbers  1,2,3,5 the Father, Son, and Holy Spirit are one thing.  But according to #4, the Father, Son and Holy Spirit are three separate things.  Unfortunately, Christians often use faulty analogies to try to explain the triune God.  For example, you have probably heard the following: “God is like an egg.  You have the shell, the albumen (white part), and the yoke, yet just one egg.” But that is a false analogy.  You end up with tripartism (1/3+ 1/3+1/3=1).

Or another false analogy is: “I am one person, but I am a father, a son, and a brother all at the same time.”  This analogy illustrates an early heresy in the Church called modalistic Monarchianism in which God is one Person who appears in three different roles.

So is the charge of skeptics and cultists a valid one?  Is the revelation of the trinity illogical and irrational, violat­ing the law of non-contradiction  (“A” cannot be “non-A” at the same time and in the same way)?

Before I begin to demonstrate the logical coherency of the revelation of the triune God, it is important to note a cou­ple of things.  It is one thing to defend the revelatory belief against charges of logical incoherence and another thing to prove it is true.  It is still another thing to explain thoroughly or completely how, in this case, God is to be understood.  We cannot prove through logic alone that the doctrine of the trinity is true.  Nor can we as finite, fallen human beings have a complete understanding  of God’s triune nature-there will  always be an element of mystery here.  Nonetheless, we can know enough, using good logic, to know that the doctrine of the trinity is not illogi­cal or absurd.

God reveals that He is one being.  And He has revealed Himself to consist of three distinct Persons (having self­ consciousness and other communicable attributes) in the Father, Son, and Holy Spirit.  He is not three beings (or “things”) but one being.  Yet, despite appearances, these truths are not contradictory.  We may see this by use of a simple illustration.  Consider an individual human being-call him John. How many beings is John? One being, of course. How many persons is John? He is one person. Now consider a chair. How many beings is a chair? One being, of course. (A “being” is defined as something having existence.) But, how many persons is the chair? Zero. The chair is not a person at all. So, if a being can be one person and less than one person at the same time, there is no logical contradiction in saying that a being could be more than one person at the same time. The same argument can be made for three persons exist­ing as one substance. 5


There are many texts in the Bible that critics say are con­ tradictory. The following list provides a few examples of some of these “problem” texts:

Jesus asks the Father not to lead us into temptation (Matt. 6:13) yet God tempts no one (Jas 1 :13).

Not everyone who calls on the name of the Lord will be saved (Matt.7:21), yet whoever calls on the name of the Lord will be saved (Rom. 10:13).

God is all powerful (omnipotent), He can do any­ thing, yet God cannot sin.

Jesus and the Father are one (John 10:30), yet the Father is greater than Jesus (John 14:28).

Jesus was God incarnate (John 1: 1,14), yet Jesus was a man approved by God (Acts 2:22).

All of these alleged contradictions arise because the Bible critic has engaged either in faulty interpretation or faulty reasoning (either bad hermeneutics or bad logic).  This is another area where a study of logic can be helpful.



Sometimes, as with the doctrine of the trinity, skeptics seek to undermine Christian beliefs by formulating argu­ments designed to show our beliefs to be false or unrea­sonable.  Here are some further examples:

The Bible is written by human authors.

Humans err.

Therefore, the Bible has errors.


God is eternal and immortal and therefore cannot die. Jesus died.

Therefore, Jesus is not God.


Jesus was a human being. All humans sin.

Therefore, Jesus sinned.


If God is all powerful, He would be able to prevent or eliminate evil.

If God were all good, He would want to prevent or eliminate evil.

So if God were both all good and all powerful, there would be no evil.

Evil exists.

Therefore, there is no all powerful or all good God.


Again, confronted with these challenges, it is incumbent upon the Christian to learn how to think clearly and cor­rectly.  ARC has published earlier issues of Areopagus Journal that are foundational to this calling.  One is an issue on the inspiration, inerrancy and authority of the Bible (“The Breath of God”-January 2002).  Another is on epistemology, the discipline of how and why we know truth (“How Do We Know?”-April 2002).  The difficult problem of evil and suffering is addressed as well (“Why, Lord?”-May-June 2005).  We also have an issue on bib­lical canonicity (“Do We Have the Right Books?”­ November-December 2005). This was followed by our last issue (“Biblical Interpretation”-January-February 2006) which deals with the science and art of proper inter­pretation of the Bible. The knowledge conveyed in these journals underscore our need expressed by the Psalmist, “Give me understanding, that I may keep your law and observe it with my whole heart” (Ps. 119:34), and the application of Jesus’ prayer for us, “Father sanctify them in the truth, for Your word is truth” (Jn. 17:17).



This issue of Areopagus Journal will build on the con­cepts introduced in past journals by giving you the tools to use good logic (think and reason well) and to point out the faulty logic and reasoning of unbelief. The first arti­cle is by W. Jay Wood, Professor of Philosophy at Wheaton College, entitled, “Virtue & Knowledge.” In this article, Jay explains the connection between the acquisition of knowledge (and avoidance of error) and the development of good habits of thinking known as intellec­tual virtues.

ARC ‘s Steve Cowan writes, “Minding Your P ‘s and Q’s: A Primer on Logic for Christians.”  In this article, Steve lays out the basic principles of logic and the most com­mon forms of rational argumentation.  He also points out some common fallacies that should be avoided.

Picking up on the theme of fallacies, Roy Massie, a grad­uate student at Birmingham Theological Seminary, con­ tributes the article, “Don’t Be Deceived: An Informal Introduction to Informal Fallacies.”  Roy explains and illustrates several of the most common misuses of human language and rhetoric designed to lead people astray.

Before reading the articles in this journal, I would encour­age the reader to take the logic self-test on page 28 to see how much logic you already know (or don’t know).  Then read the articles and try the test again.

Craig Branch is the Director of the Apologetics Resource Center in Birmingham,  Alabama. (at the time of publication)


1      Patrick J. Hurley, A Concise Introduction  to Logic, 4th ed., (Belmont, Calif: Wadsw01ih, 1991),  1.

2  Irving Copi, Introduction to Logic, 7th ed., (New York: MacMillan, 1986), 3, 5.

3  Gordon H. Clark, Logic, 2nct ed. (Jefferson MD: Trinity Foundation, 1985), 1.

4 J.P. Moreland, Love Your God with All Your Mind: The Role of Reason in the Life of the Soul (Colorado Springs, CO: NavPress, 1997), 21. I would add to Moreland’s list “illogical rhetoric.”

5 For a thorough Scriptural exposition on the revelation of the Triune God, ask us for our free information packet on the Trinity (,), and see the article by Ron Rhodes, “Defending the Deity of Christ and the Trinity against the Jehovah’s Witnesses,” Areopagus Journal  5:4 (July-August  2005): 23-28.