Theistic Apologetics


Dennis McCallum and Gary DeLashmutt

There are three major approaches to theistic apologetics in common use today. They are the Classical approach, the Evidentialist approach, and the Presuppositional approach.



Section 1 - Classical Apologetics

Modern Classical Apologists include Charles Hodge, B.B. Warfield, Charles Hartshorne, F. R. Tennant, Norman Geisler, R.C. Sproul, and John Gerstner.

The importance of studying classical apologetics stems from the fact that most secular philosophy courses only dialogue with the classical arguments. In addition, Classical Apologetics are an item of dogma for the Roman Catholic Church. As Christiani puts it,

"Before starting to examine modern forms of apologetics,... Are such forms permitted; are they lawful?...Yes, but with a few conditions: first, they do not contradict classical apologetics and, secondly, that they are in some way connected with it. No one may reject classical apologetics, for, as we have seen, it has been sanctioned by the Vatican Council, and the principles then laid down have been repeated by St Pius X in his Encyclical Pascendi. These two documents, which we must not reject, indicate the proper end for Catholic apologetics, and the essential means for gaining this end."[footnote 1]

As a result of these two facts, most students today are led to believe that these arguments are the main line of Christian defense, even though many of them are not particularly effective. Classical apologetics should be understood then, not only for use in evangelism, where appropriate, but also in order to be prepared to critique some of the weaker arguments.

There are three classical arguments for the existence of God.

I. The Ontological Argument

A. Explained

This argument attempts to prove that the existence of God necessarily follows from the idea of God.

Proslogion 2 form (positive form):[footnote 2]

  1. Everyone can conceive of God (the infinite, eternal necessary Being of Scripture).
  2. God is that being, greater than which cannot be conceived.
  3. A non-existence God is not that greater than which cannot be conceived, because a greater God can be conceived-- one who does exist.
  4. Therefore God exists.

Descartes' Meditation #3 (another positive form)

  1. Everyone can conceive of God.
  2. The idea of God is that of an infinite perfect unlimited Being.
  3. For everything there must be a cause as great or greater than the effect.
  4. Therefore, for the idea of God which we have, there must be an infinite, perfect, unlimited cause.
  5. But we are not infinite, perfect or unlimited--and thus could not create such an idea ourselves.
  6. Therefore there must be a cause outside of ourselves, which is infinite, perfect, and unlimited, which caused the idea of God which we have in our minds.
  7. This Cause is the God of the Bible

Proslogion 3 form (a negative form)

  1. No contradictory thing can be conceived of.
  2. No inconceivable thing can exist (where inconceivable because contradictory).
  3. God is by definition the greatest thing which can exist.
  4. God either exists just as an idea, or really exists.
  5. To really exist is greater than to be just an idea.
  6. Therefore a God who is just an idea is a contradiction in terms.
  7. Therefore a God who is just an idea is inconceivable.
  8. Therefore a God who is just an idea cannot exist.
  9. Therefore God must really exist.

B. Critiqued

The Ontological argument is not effective and should not be used.

  • We cannot deduce the existence of a being from the idea of that being. The attempts to do so usually involve untrue premises or conclusions that do not follow from the premises. 
    • In Proslogion 2 form, #4 does not necessarily follow from #1-3.
    • In Descartes' Meditation #3, premise #3 is unproven. Further, it is the God we think of that is perfect, not our thought of Him. This undermines #4. Conclusion #6 is false. We are not claiming to understand infinity, only to be aware of it.
    • In Proslogion 3 form, step #5 is neither a logical conclusion nor an axiom, but an unproven value judgment.

II. Teleological or Design Argument

A. Explained

Argues that the presence of order in the universe requires the existence of an orderer.

A typical formulation of the argument.

  1. The universe manifests evidence of design.
  2. All design demands a designer (which entails x,y,and z characteristics).
  3. Therefore, the universe must have a designer.
  4. This designer is the God of the Bible.

Paley's Watch argument.[footnote 3]

  • While walking through a field, one finds a watch on the ground. He naturally and rightly concludes that it had a watchmaker. Likewise, if one studies the more complex design in the natural world, he cannot but conclude that there is a world Designer behind it.

B. Critiqued

There are limitations to the teleological argument that we should be aware of. However, if used properly, this argument can be helpful.[footnote 4]

  1. David Hume produced effective criticisms of the teleological argument in his essay, "Dialogues Regarding Natural Religion."[footnote 5] The main salient points were that 
    • The term "design" needs to be defined. He shows that there is unavoidable subjectivity involved in the concept of design. Two observers can look at the same thing without agreeing that it shows design. Any universe must have "design" in order to exist. Can we describe what a universe without design would be?
    • It is also claimed that the theist selects some features in the universe to demonstrate that God must have made them, but attributes other features of the world (such as evil and suffering) to man. This is seen as special pleading. Special pleading means that one side of an argument is claiming rules for itself which it will not extend to the other side. In other words, it is improper to point to the nature of the cosmos to prove the existence of God, but to plead that some of the features of that cosmos must be excepted.
    • It is argued that the presence of whatever design there is, might be an isolated exception. Perhaps we are an island of design in a vast ocean of chaos. This argument is pointing to the difficulty inherent in the area of probability. No matter how improbable something is, it could still happen. If a million-sided dice is rolled, then any number that comes up is one chance in a million. Yet, it did come up on the first roll! A person could also win the state lottery even though it is unlikely. In the same way, our own world may have occurred by chance, no matter how unlikely.
    • Paley's watch argument is attacked on the basis of special pleading as well. What makes the watch stand out in the field where it is found? If the answer is "the presence of design", then it is evident that the design of the watch set it apart from the rest of the field-- (that is, the watch shows design, while the field does not). How then can the watch be used to demonstrate that the field has design, when it is the difference between the watch and the field that drew our attention to it in the first place?
  2. The main problem with the teleological argument is the effort usually made to frame it as an inescapable deductive proof of theism. It would be far better to frame this argument as an inductive argument which points to the presence of a designer as one of the more likely explanations for apparent design. This has to do with the "burden of proof" issue: namely, that the Christian need show no more proof for his position than anyone else.
  3. Although the teleological argument makes the existence of a designer likely, the argument by itself does not lead necessarily to belief in biblical monotheism. It could, for instance, also support polytheism.
  4. Critics feel the Darwinian theory of natural selection has destroyed the teleological argument, by showing that changes come from purely natural causes rather than by special design. This is not true. While natural selection may account for which forms "survive", it cannot account for which forms "arrive". Stated differently, a distinction must be made between change within given levels of complexity, versus the emergence of new levels of complexity. For example, a screw cutting machine may accidentally produce a backward threaded screw. However, it will not produce a T.V.!

III. The Cosmological Argument

A. Defined

The Cosmological argument differs from the Teleological argument in that it considers why anything exists whereas the Teleological considers the nature of what does exist.

A summary of Geisler's Cosmological Argument (a deductive argument with an a posteriori first premise)

  1. Some contingent [dependent] beings exist
  2. All dependent beings must have a cause or explanation for their dependent existence (cf. Principle of Sufficient Reason)
  3. An infinite regress of existentially dependent causes is impossible
  4. Therefore there must be a first uncaused Cause of the dependent beings.
  5. This Uncaused Cause is the God of the Bible.

Sproul's cosmological dilemma

Either the Universe is:

  1. Illusion - (but I think, therefore I am - Who is thinking of non-existence?)
  2. Spontaneously Generated - (but this is an unthinkable thought, because it is an effect with no cause)
  3. Eternal - (but it would still need a cause)
  4. Created by something eternal.

A simpler statement

  • It is assumed in science and reasoning that any effect or event must have a cause. Since the universe is an effect, or result, then the universe as a whole has a cause. 
    • Illustration - A 10' wooden ball would seem to require a maker, or a cause for its existence. It should be clear that one several times as large also requires a cause. If a 100 foot ball would require a cause, how much more a ball 25000 miles in diameter, not to mention, one the size of the universe?

Scientific Arguments

  1. The scientific laws governing energy transfer (thermodynamics) suggest that the amount of energy in the universe is constant, though changing in form.  
    Furthermore, in all closed systems we observe a leveling process. Physicists point out that there is a universal tendency toward greater entropy. This means, among other things, that the amount of energy available for use is always decreasing. In a sense, the Universe is running down, which means that the universe should eventually reach a state of complete entropy.  
    This implies that the Universe is not eternal, because if it was eternal, it would have reached a position of complete entropy an eternity ago. This suggests that the Universe had a cause which is beyond itself.[footnote 6]
  2. The "red shift" Doppler effect shows astronomers that the universe is expanding. Such movement could not have been in progress forever. This is the origin of the so-called "big bang" theory, which is more or less axiomatic today.  
    There is no known reason why a big bang would have occurred, or why the present inertia of the stars would ever reverse direction, as in the theory of the oscillating universe. This is to say that the theories that might account for such oscillation are unproven, and involve phenomena which have never been observed.

B. Critiqued

The main critique of the cosmological argument is that it involves special pleading.

  1. If everything requires a cause, then God requires a cause. If God requires no cause, then not all things require a cause. 
    • However, if it can be shown that the eternal existence of God is different than the eternal existence of the Universe, this argument might hold up.  
      John Hick has argued that since God is personal, He is not subject to natural law, (e.g. thermodynamic laws) which apply to the physical realm. Therefore, there are fewer problems with His eternity than there would be with the eternity of the physical universe.[footnote 7]
  2. The position taken in the cosmological argument regarding an infinite regress of cause and effect (namely that an infinite regress is not possible because the whole string requires a cause) fails to come to grips with the word "infinite". If a cause and effect chain is infinite, then the reason for it is always the previous cause. To appeal to any outside cause is to beg the question entirely.
  3. The appeals to scientific laws and to the big bang are primarily useful for showing that there are problems with the naturalistic view. They do not prove the existence of God. However, by comparing the theistic model with the naturalistic model in the light of these laws of nature, it is possible to show that theism would remove some problems that naturalism cannot. the result is greater probability for theism.


The classical arguments cannot prove the existence of God. If they could, the explanation would be pages long, and incomprehensible to the average man. Finally, if classical apologetics could prove the existence of God, it would not necessarily be the God of the Bible.

Section 2 - Evidentialist Apologetics

Evidential Apologetics are the product of the rise of modern science and modern historiography. During the period of the enlightenment, Christians were eager to show that a scientific approach to Christianity was possible.

The type of scientific method used was a forensic, or inductive approach, which is similar to courtroom evidence. Forensic science collects evidence after the event (e.g. an autopsy) and seeks to find the most plausible explanation for the event. Such an argument does not claim to "prove" Christianity, but only to render it probable.

Today, Evidentialism is the main approach in use in American fundamentalist and evangelical circles. Spokesmen for the approach include Josh McDowell, C. S. Lewis, John W. Montgomery, Clark Pinnock, Hal Lindsey, and many others. Many other author's combine evidential arguments with other approaches.

An Evidentialist Argument

A. The Historical Argument (an inductive argument with a posteriori premises).
  1. Historiography, textual criticism, archaeology, etc. demonstrate that the Bible is a reliable history book.
  2. The Bible teaches that Jesus lived, and claimed to be God.
  3. Jesus could only be (l) Lord, (2) a liar, (3) a lunatic
  4. Various parts of the description of Jesus' conduct and the response to his character rule out his being a lunatic.
  5. Other parts of his conduct and a lack of clear motive rule out his being a liar.
  6. Therefore Jesus was whom he said he was: Lord, and God.
Additional Steps, tending to add verification to steps 4,5,6
  • Jesus fulfilled prophecy in a way that a liar or lunatic could not
  • Jesus performed miracles in a way that a liar or lunatic could not
  • The historical fact of the empty tomb and the resurrection account cannot be explained if Jesus was a liar or lunatic
  • The phenomenon of the faith, integrity, and sacrifices of the early Church cannot be explained if Jesus was a liar or lunatic
Critique of the Evidentialist Approach

The evidentialist approach has strengths in certain contexts. It is used in Scripture, by Christ, the Old Testament, and by the apostles.[footnote 8] However, it is essential that the Christian apologist realize some limitations of this method.

  1. Modern evidentialist apologists have made exaggerated claims regarding our ability to verify the historicity of the Gospels. Although we can demonstrate relatively good historical value in the gospels, it would be a mistake to think that secular scholars will be impressed to the extent that they would accept supernatural aspects of the narrative. 
    • Evidentialists have failed to point out that the Gospels lack one feature that is considered important for credibility by modern historians-- namely correlation. That is, even though the gospels can be correlated with other sources regarding geography and non-Christian historical facts, they can not be compared with outside sources regarding the words, acts, and character of Jesus. This does not mean that the gospels are not historically sound. It only means that they are not as iron-clad as some authors have claimed.
  2. The empty tomb argument is based in part on an argument from silence. This fact is mitigated somewhat by the fact that it is a conspicuous silence (because the body could have been exhumed) but it remains a sore point which has not been admitted or dealt with by evidentialists.
  3. The Lord Liar Lunatic dilemma is not a very strong argument from the standpoint of cogency. On the other hand, it is effective in confronting the hearer with his choices, and eliminating the likelihood of the "good man" theory. It does not usually deal with the legend theory sufficiently.
  4. Some Evidentialists have a reputation for credulity and deliberate distortion, especially when citing authorities who supposedly agree with the position taken, when they actually do not. There are even cases of gross misinterpretation and quotations taken out of context apparently on purpose. The work of many evidentialists has the appearance of "working from the bottom line up" (looking for anything that will prove the point) rather than careful scholarship.[footnote 9]
Strengths of the Evidentialist Approach

There are appropriate uses of the evidentialist approach. The main thing is to avoid attempting to make the evidences do more than they can legitimately do. This has to do with the burden of proof question.[footnote 10]

  1. The evidential arguments have strengthened the faith of many Christians.
  2. When addressing non-Christian's, the argument from fulfilled prophecy is the best part of the evidentialist argument to use. This argument has definite value in terms of establishing the likelihood of biblical revelation and the uniqueness of Christ.
  3. Evidentialist arguments can and should be used to create curiosity and willingness to hear a more complete presentation of biblical teaching. They should also be used to correct the misconception that Christianity is without evidence. They are, in other words often pre-evangelistic in scope.

Section 3 - Presuppositional Apologetics

Presuppositional apologetics have become prominent in recent years due to the work of several reformed scholars including Cornelius Van Til, Gordon Clark, E. J. Carnell, and Francis Schaeffer.

At a time when classical apologetics are in general discredit among scholars in the secular world, presuppositionalism has enjoyed increasing respect in scholarly circles. Modern Christian communicators should read a good selection of the writings of these authors, and become able to employ this approach when appropriate.

I. Presuppositional Theory

The central idea behind presuppositional apologetics is the fact that everyone does have certain presuppositions, no matter what their world view. This fact is obvious, although the exact presuppositions held in a given case may not be obvious. It is even possible that the presuppositions are not clear to the one that holds them. Therefore, there often needs to be a step of discovery of the other's presuppositions before applying the method.

In some models (Van Til's for instance) there is the assumption that the presuppositions of all non-theists are the same. In others, this question is left open at first.

II. Presuppositional Models

Van Til's Presuppositional Method[footnote 11]
  1. Gain awareness of each other's presuppositions (epistemological self-consciousness) and of their absolute difference.
  2. Place oneself upon the presuppositions of the unbeliever for arguments sake--show that they do not provide an adequate reference point for predication (i.e., a sufficient base for reasoning at all).
  3. Show that on Christianity's presupposition (the ontological Trinity as ultimate Creator and Interpreter), rationality is upheld. Only Christianity does this (facts and laws analysis).
  4. Press the claims of the Gospel. 
    • Point out that since rational conversation has gone on, the unbeliever must abandon his presuppositions and adopt Christian ones.
    • Point out why unbelieving presuppositions were chosen, and call for repentance and faith.
Schaeffer's One on One Approach[footnote 12]
  1. Establish communication and common meanings.
  2. Dialogue to discover the other's presuppositions.
  3. Carefully push the non-Christian's presuppositions to their logical conclusion with an attitude of compassion.
  4. Find the point of tension, pressing the unbeliever to compare the logical conclusion of his beliefs to the real world, himself and his actual conduct.
  5. Show that the Christian world-view better allows him to live in the real world, thus suggesting that this world view is true.
Communication Guidelines

It is the view of this author that presuppositional apologetics are a better argument than most other approaches in the area of cogency (i.e. being convincing). However, most evangelists find that there are problems using this approach in witnessing.

One problem that is frequently encountered is that the hearer becomes argumentative and resistant if he feels that he is being "bested" in a debate. In other words, the presuppositional approach is confrontative, and therefore runs the risk of further agitating the ego of the hearer. He begins to feel that he must not only submit his ego to God, but also to the apologist.

It is therefore recommended that the presuppositional approach be used especially in cases where resistance is being encountered, or where an argumentative attitude is already evident. Another situation that is good for a presuppositional argument is public speaking. In this case, since the opponent is imaginary, the crowd is not provoked to ego-involved behavior.

Another problem has to do with the difficulty of establishing step #3 in Van Til's method or #4 in Schaeffer's method. These are sophisticated arguments that can be hard to simplify unless they are understood well. Additional reading is imperative if this ability is to be acquired. An example of how this is done can be seen in the following example.

Taylor's Explanation of the Effects of Theistic Presuppositions on Epistemology

Suppose that you are riding in a railway coach and glancing from the window at one of the stops, you see numerous white stones scattered about on a small hillside near the train in a pattern resembling these letters: THE BRITISH RAILWAYS WELCOMES YOU TO WALES. Now you could scarcely doubt that these stones do not just accidentally happen to exhibit that pattern. You would, in fact, feel quite certain that they were purposefully arranged that way to convey an intelligible message.

At the same time, however, you could not prove, just from a consideration of their arrangement alone, that they were arranged by a purposeful being. It is possible -- at least logically so -- that there was no guiding hand at all in back of this pattern...It is possible that the stones, one by one, rolled down the hill and, over the course of centuries, finally ended up in that interesting arrangement... For surely the mere fact that something has an interesting or striking shape or pattern, and thus seems purposefully arranged, is no proof that it is . . . .

(So far, this is a standard teleological argument. What follows is the connection between the teleological and the presuppositional arguments.)

Here, however, is the important point which it is easy to overlook; namely, that if, upon seeing from the train window a group of stones arranged as described, you were to conclude that you were entering Wales, and if your sole reason for thinking this, whether it was in fact good evidence or not, was that the stones were so arranged, then you could not, consistently with that, suppose that the arrangement of the stones was accidental. You would, in fact, be presupposing that they were arranged that way by an intelligent and purposeful being or beings, for the purpose of conveying a certain message having nothing to do with the stones themselves. Another way of expressing the same point is, that it would be irrational for you to regard the arrangement of the stones as evidence that you were entering Wales, and at the same time to suppose that they might have come to that arrangement accidentally, that is, as the result of the ordinary interactions of natural or physical would be irrational for one to say both that his sensory and cognitive faculties had a natural, non-purposeful origin and also that they reveal some truth with respect to something other than themselves, something that is not merely inferred from them.[footnote 13] (emphasis mine)

A sound presuppositional apologetic belongs in the arsenal of the modern Christian communicator, because it is frequently very effective in public speaking, and in gaining respect in one on one conversations, especially with well educated and intelligent hearers.


1. Msgr. Leon Cristiani, Why We Believe (New York,NY: Hawthorn Books,1959) p.96

2. Condensed by Douglas Chismar, "Resource Materials, Christian Apologetics". (Unpublished course notes, Ashland Theological Seminary, 1985) p.3 A fuller discussion can be found in Hick, Arguments for the Existence of God. See note #6 below.

3. William Paley, Natural Theology, cited in Geisler, Norman L., Christian Apologetics, (Grand Rapids, Michigan: Baker Book House Company, 1976) pp.88,89

4. uses a basic form of this argument in Romans 1:18-20.

5. David Hume, Hume's Dialogues Concerning Natural Religion. (Oxford: Clarendon Press, 1935).

6. It is important to remember that the second law of thermodynamics only applies to a closed system. Since the earth is not a closed system, (in that it is open to energy input from the sun etc.) this argument cannot be used to attack evolution on earth.

7. John Hick, Arguments for the Existence of God. (New York: Herder and Herder, 1971) pp.34 ff. He also gives other reasons for distinguishing between God and the universe in the area of eternalness.

8. For a use of prophetic evidence by God in the Old Testament, see Isaiah 41:22-29; 42:9; 44:7, 24-25; 45:21; 46:8-10; and 47:12-15. In these remarkable passages, God shows that His chosen method of self verification would be predictive prophecy. The passages are interspersed with the four anonymous servant songs which, according to the New Testament, refer to Christ.  

For usage of this method by Christ, see Luke 24:44 where Jesus points to the Old Testament, as well as to his own words as providing verification through prediction.  

For the apostles, Acts 17:2-3 shows that Paul customarily reasoned from the scriptures, citing predictive prophecy of Christ in order to persuade his audience. 1 Corinthians 15:1-8 is an evidentialist argument based on eyewitness accounts, and predictive prophecy. 1 John 1:1-3 and 2 Peter 1:16-21 are also evidentialist arguments.

9. Note that the young earth position is usually argued using exactly the same evidentialist techniques used to prove the deity of Christ.

10. See my paper "An Approach to Apologetics"

11. Condensed by Douglas Chismar, "Resource Materials, Christian Apologetics". (Unpublished course notes, Ashland Theological Seminary, 1985) p.4

12. Douglas Chismar, "Resource Materials, Christian Apologetics". p.5

13. Quoted in John Hick, Arguments for the Existence of God, pp.23,24