Christian Apologetics in a Nutshell


Douglas Groothuis

Article ID:



Mar 7, 2023


Sep 13, 2021

This article first appeared in the Christian Research Journal, volume 42, number 3/4 (2019). For further information or to subscribe to the Christian Research Journal please click here.


Christians are called to make a rational case for their worldview. This task of Christian apologetics is too important to be left to big textbooks read by few people. Christianity is intellectually strong and can be summarized for ready access and as a means for further study and application. Reason and evidence are available in the defense of Christianity as objectively true, compellingly reasonable, and pertinent to the whole of life. The Bible encourages apologetics, and Jesus Himself was a masterful apologist. The apologist must be a person of Christian integrity and love in order to make the gospel attractive. What she defends is the Christian account of reality, which can be summarized in terms of creation-fall-redemption-consummation. The best method for defending the Christian worldview is the cumulative case method — many strands of argument tie together to verify its truth. Apologists can establish the existence of God through several arguments including the moral and kalam cosmological arguments. One should also defend the reliability of the Bible and the extraordinary and unparalleled claims and credentials of Jesus, particularly His death-defeating resurrection. While critics argue that the problem of evil is fatal to Christianity, Jesus’ death and resurrection provide the best answer and greatest hope for those who suffer. For these and many other reasons, the defense for Christianity must never rest until Christ comes again.

There is no nutshell big enough for a sufficient defense of Christianity. Nevertheless, some things need to be squeezed into a nutshell rather than be ignored. A summary of the case for Christianity may inspire readers to develop their own apologetic for the glory of God. Having spent eight-and-a-half years writing a voluminous textbook on apologetics, I will give it a whirl.1


The Bible is an apologetic book and urges the church to be an apologetics church. Apologetics comes from a Greek word apologia, which means to give a rational defense of a belief. Peter uses a form of this word in the locus classicus for apologetics: “Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have” (1 Pet. 3:15, emphasis added).2 Apologetics is the task of showing that Christianity is objectively true, compellingly rational, and pertinent to the whole of life.

Jesus was an apologist and philosopher, defending His views under fire and outwitting His opponents repeatedly.3  Peter and Paul followed Jesus’ example by defending the gospel in the Book of Acts. They, too, were filled with the Holy Spirit, who is the Spirit of Truth (John 14:16–17). Paul’s sermon to philosophers in Athens is a masterful piece of apologetic reasoning that has inspired a score of Christian apologists over the ages (Acts 17:16–34).4 In this same spirit, Christian thinkers from Saint Augustine to C. S. Lewis have been brought to faith through apologetics. Surely, apologetics is part of God’s mission to restore shalom to a rebellious planet through the work of Jesus Christ!

The Character of the Apologist

Peter tells us to do apologetics “with gentleness and respect, keeping a clear conscience” (1 Pet. 3:15–16). The gospel offends the pride of an unbeliever, but apologists should never offend anyone because of their pride. Paul tells Timothy to guard the gospel and to refute false beliefs, but that his “opponents must be gently instructed, in the hope that God will grant them repentance” (2 Tim. 2:25). Love sets the agenda for apologetics.

Love is a fruit of the Holy Spirit that must undergird every gift of the Holy Spirit. We are called to speak “the truth in love” (Eph. 4:15), not in arrogance.5


Apologetics must clarify what it defends. Christianity is summarized in the creation/fall/redemption/consummation model, which is both a story and a metaphysic. A personal, infinite, and triune God created the universe and made humans in His own image and likeness (Gen. 1–2). But God’s own image-bearers turned against Him, bringing sin and evil into the world (Gen. 3). Nevertheless, God continued to pursue and interact with fallen humanity by revealing Himself in nature, by sending the prophets, through His creation of the nation of Israel, by sending the long-awaited Messiah, Jesus Christ, who bled and died to redeem people for God. We know this through the propositional truth of the Bible. In the end, God will bring all things to consummation by purging and redeeming the universe (Isa. 61; 1 Cor. 15; Rev. 21–22).6


Apologists argue about how to argue for Christianity (apologetic method), but I will simply offer my approach, which is rooted in extensive academic and ministry experience.7 A cumulative case approach to apologetics defends Christianity through various arguments from several fields, such as science and history. We test the Christian worldview and all worldviews by applying three basic criteria: (1) internal consistency, (2) factual adequacy, and (3) existential livability.8 The defining claims of any worldview must agree with each other, they must match the reality of the objective world, and they must be consistently livable in a life-giving way.

Objective Truth and Natural Theology

The apologist needs to defend an objective account of truth. If everything is relative, Christianity cannot claim to reveal objective truths in its worldview. But we know that the basic principles of logic and morality are not relative. On this basis, our apologetic enlists various arguments for the existence of God through the discipline of natural theology. Since the cosmos testifies to its Creator and Designer (Ps. 19:1–6; Rom. 1:18–21), we can construct arguments from nature and science for God that show Him to be the Creator, Designer, and Source of morality, and Object of religious experience, among other attributes.

Two Arguments for God’s Existence

Arguments for God will not tell us everything we need to know about God. However, they form part of the total case for the Christian worldview, along with arguments for the truth of the Bible and the deity of Christ.9

A Cosmological Argument. One of the most discussed and cogent arguments for God’s existence is the kalam cosmological argument.

  1. Whatever begins to exist has a cause of its existence.
  2. The universe began to exist.
  3. Therefore, (a) the universe has a cause of its existence.
  4. Therefore, (b) God exists as the cause of the universe.

The first premise is true since something cannot come from nothing. The second premise is supported by both philosophical reasoning and scientific evidence for the absolute origination of the cosmos a finite time ago.

The scientific case for the beginning of the universe is based on the standard model of cosmology or what is called the big bang. Several converging lines of evidence have firmly established this cosmology, which is interpreted by most to require an absolute origination of the universe from nothing about fourteen billion years ago.10 Here are highlights.

Einstein’s general theory of relativity (1917) contained an error that when corrected predicted an expanding universe. In 1929, American astronomer Edwin Hubble detected the “red shift” in distant galaxies, which indicated that what was further away was moving at a greater speed. This provided more evidence for an expanding universe. The detection of cosmic background radiation was found to be left over from the beginning of the universe, which came to be called “the singularity.” The upshot of this evidence and more was stated by Barrow and Tipler. “At this singularity, space and time came into existence; literally nothing existed before the singularity, so, if the Universe originated in such a singularity, we would truly have a creation ex nihilo [out of nothing].”11

We may infer that the cause of the cosmos is a timeless and spaceless personal agent of unlimited power who is, of course, outside of the universe. In other words, “In the beginning, God created the heavens and the earth” (Gen. 1:1; see John 1:1–3). The kalam argument does not speak to God being a Trinity or say much about His moral character, but it is more than a good start. Other arguments do other kinds of work in the cumulative case.

A Moral Argument. We are created beings. That should humble us. Something within our consciousness speaks of God as well. Women and men throughout all recorded history have experienced conscience, a moral monitor regarding thoughts and behavior. Our ancestors and our neighbors give moral praise and blame. Guilt has been a universal condition of our species. Those with a conscience tutored by the Bible and those without the Bible know this experience (see Romans 2:14–15).

Conscience speaks to moral standards and obligations beyond the self and even society. Moral relativism denies such values and duties by claiming that morality is reducible to cultural influences. There are no objective, absolute, and universal moral standards and obligations. If so, God has nothing to do with morality. But relativism is demonstrably false.

Some moral statements are unquestionably true, such as “rape is wrong,” and “parents should be responsible for their children.” If so, relativism is untrue because these statements are binding unconditionally on everyone. Moreover, the very ideas of moral progress or regress must assume an unchanging objective standard against which societies are judged. Without this standard, the abolition of slavery would be merely change and not progress. That is ridiculous. Lastly, despite disagreements within and between cultures on moral matters, there is general agreement on basic moral principles. As C. S. Lewis wrote: “Think of a country where people were admired for running away in battle, or where a man felt proud of double-crossing all the people who had been kindest to him. You might just as well try to imagine a country where two and two made five.”12

Morality needs an explanation beyond the human-all-too-human realm. Its authority is found elsewhere. But God, the eternal source, standard, and stipulator of the good, defines what is good according to His nature and purposes. He has revealed this objective morality in conscience and in Scripture.


If God created the universe and if He is the authority behind morality, then God is able to reveal Himself further through other means, such as through history and in documents. The Christian apologetic is completed by the truths found in the Bible. An adequate defense of the authority and wisdom of the Bible is beyond this essay, but a few points suffice.13

No apologetic would be complete without a defense of the Bible on the basis of historical, literary, and archaeological evidence. And yet the stories, statements, questions, parables, and poems of the Bible carry conviction in and of themselves. Because of this, a stout and fair reading of Scripture — and particularly the Gospels — is strong medicine against sad caricatures and ignorant dismissals of Holy Writ. The same goes for hearing strong expository preaching.14 Since it is God’s living revelation of truth, the Bible speaks to our condition as does nothing else.

The greatest story ever staged was written, produced, and acted out by God Himself, as the Bible tells us. In the marvelous words of Dorothy Sayers, “the dogma is the drama.”

For whatever reason God chose to make man as he is — limited and suffering and subject to sorrows and death — He had the honesty and the courage to take His own medicine. Whatever game He is playing with His creation, He has kept His own rules and played fair. He can exact nothing from man that He has not exacted from Himself. He has Himself gone through the whole of human experience, from the trivial irritations of family life and the cramping restrictions of hard work and lack of money to the worst horrors of pain and humiliation, defeat, despair and death. When He was a man, He played the man. He was born in poverty and died in disgrace and thought it well worthwhile.15

For those skeptical of the Bible, we can dissipate several misconceptions, starting with the New Testament. Nothing of major concern has been lost in the translation or transmission of the documents. The objection that the Bible is unreliable because “it has been translated so many times” is empty. Modern translators draw from about six thousand ancient manuscripts taken from the original Greek language, far more than for any other ancient document. Only a small fraction of the texts — called marginal readings — of modern translations are in question. Further, the major translations of the Bible — such as the New International Version and the New American Standard Bible — differ somewhat in style but almost never in meaning.

The books of the New Testament do not read as myths or legends. As Sayers says, in Egyptian and Greek savior myths “the god is supposed to have suffered and died in some remote and mythical period of pre-history….The Christian story, on the other hand, starts off briskly in St. Matthew’s account with a place and a date: ‘When Jesus was born in Bethlehem of Judaea in the days of Herod the King.’”16

Although these accounts contain miracles, the internal test tells us that they fit the genre of history. The authors of the Gospels were either Jesus’ apostles (Matthew and John) or closely associated with an apostle (Mark and Luke), and they wrote only a few decades after the events they describe. There was no time for legendary material to creep in — as it did in second– and third–century stories about Jesus. The Gospels differ in style and content, but overlap on all the key points about Jesus. Most of the supposed contradictions among them can be harmonized easily. Others require some work.17

The figure who towers over the Bible is Jesus of Nazareth. He cannot be stuffed into the same category as other religious founders or leaders, given His claims and credentials. While He was a prophet (speaking truth to power and to the powerless) and a sage (a man of deep wisdom), He was more. Nature, illnesses, and demons obeyed His supernatural word.

He amazed the crowds with the penetrating authority of His teaching — and what teaching it was! The meek will inherit the earth. The last shall be first. Enemies must be loved and prayed for. Heaven and earth will pass away but His words will never pass away. All will face Him at the end of history and give account. The gates of hell will not prevail against His church. He fulfilled the law and the prophets. Christ was a “controversialist,”18 but He was neither a sensationalist nor an


Most controversial of all, He claimed to be more than a man. He had the authority to forgive sins, a prerogative of God alone (Mark 2:1–12). He was also “the Lord of the Sabbath”; since God ordained the Sabbath, He was claiming deity (Mark 2:23–27). His response “Before Abraham was, I am” provoked His hearers to take up stones to kill Him (John 8:58). This was because Jesus was taking for Himself the divine name of “I Am” from Exodus 3:14. In situations unthinkable in the militantly monotheistic religion of His day, Jesus accepted worship on several occasions, as when Thomas said to Jesus, “My Lord and my God!” (John 20:28).

Since Jesus made these titanic assertions, we need to see if they are true. We have but three options. (1) He was lying and knew it; (2) He was mentally imbalanced; or (3) He was who He said He was. Jesus’ well-documented character eliminates (1) and (2). Ergo, He was God Incarnate.19

Jesus’ gospel was radical good news for fallen humanity. While Jesus encouraged eye-popping good works, He never endorsed them as the means of salvation (Matt. 25:31–46). Instead, He said, “The Son of Man came to seek and to save the lost” (Luke 19:10) and “to give his life as a ransom for many” (Mark 10:45).

For all other religious leaders, death was the end. For Jesus, it was the seal of His purpose and the beginning of a new order of existence and the redemption of sinful people. He predicted, “The Son of Man must be delivered over to the hands of sinners, be crucified and on the third day be raised again” (Luke 24:7). He promised that whoever “believes in him” has eternal life, having entered into eternal life through God’s love (see John 1:12–13; 3:16; 5:24).

The vindication of all that Jesus said and did was His resurrection from the dead in history (Rom. 1:1–4). All four Gospels testify to the factual reality of the resurrection. Given my previous arguments for the existence of God, we need not rule out God acting supernaturally in history. That is, miracles are possible. The earliest written record of the resurrection is found in Paul’s first letter to the Corinthians in which he cites even earlier sayings that Jesus had risen from the dead (see 1 Cor. 15:3–8). There was no time for legends to build up or for stories to be retold and distorted.

Non-supernatural explanations for the resurrection accounts and beliefs of the early church fail to explain the known facts, upon which the majority of critical scholars agree: Jesus’ burial in a known tomb, the empty tomb, the appearances to the disciples, and the key features of the early church, including baptism and communion, both of which assume the resurrection occurred.20

No other sage, guru, prophet, or seer from any other religion can match the claims, credentials, and achievements of Jesus Christ. He stands alone, and the wise person bows before Him — only to be raised to life at the last day (see John 5:28–29; 6:39).


The existence of evil in the world poses the greatest challenge to Christianity, since the Bible claims that God is both all-good and all-powerful. If so, would God allow so much evil of so many kinds into His world?

No other worldview explains the origin, purpose, and outcome of evil better than Christianity. In outline, evil came into the world through the rebellion of the creature against the Creator. God did not create evil as He did the universe. Nor is evil an illusion, as pantheists claim. Yet again, it is not a mere surd in a meaningless universe, as honest atheism must admit.

The Creator and the source and standard of morality will not waste anything. He redeems what is redeemable. To prove this, He sent His Son into the world to die in our place by suffering the worst possible dying and death. Christ’s death cry, “My God, my God, why have you forsaken me?” (Matt. 27:46) was the lament of laments, but it was not the last word for Christ or for the world He came to save. In this redemptive suffering, suffering was freed from futility. God did not stand idly by a world lost in suffering. As Sayers said, Christ took His own medicine — and we can receive the cure. The world will be set to rights when Christ comes again to judge the living and the dead. Nothing will escape God’s audit and administration of justice and mercy.

Nutshells and Apologetics

Our apologetic nutshell is stuffed full. The task of apologetics is great but the case for Christianity is strong. This should animate Christians to defend ardently what they believe and why they believe it. The defense should never rest until God Himself has the final word at the end of time.

Douglas Groothuis is Professor of Philosophy at Denver Seminary and the author of Christian Apologetics. 


  1. For what follows, see Douglas Groothuis, Christian Apologetics: A Comprehensive Case for Biblical Faith (Downers Grove, IL: InterVarsity Press, 2011). I have added new material.
  2. All Bible quotations are from the NIV.
  3. See Douglas Groothuis, “Jesus as Philosopher and Apologist,” Christian Research Journal 25, 2 (2002),; and Douglas Groothuis, On Jesus (Belmont, CA: Wadsworth, 2003).
  4. Groothuis, Christian Apologetics, 34–37.
  5. See Francis A. Schaeffer, The Mark of the Christian (Downers Grove, IL: InterVarsity Press).
  6. Groothuis, “The Christian Worldview,” Christian Apologetics.
  7. Groothuis, Christian Apologetics, 60–70.
  8. Groothuis, Christian Apologetics, 52–60.
  9. See Andrew I. Shepardson, Who’s Afraid of the Prime Mover? Postmodernism and Natural Theology (Eugene, OR: Pickwick Publications, 2019).
  10. See Michael G. Strauss, “Did the Universe Really Have a Beginning?” in this issue of the Christian Research Journal, 32–39.
  11. John Barrow and Frank Tipler, The Anthropic Cosmological Principle (Oxford: Oxford University Press, 1986), 442.
  12. S. Lewis, Mere Christianity (New York: HarperOne, 2015), 7.
  13. See Craig L. Blomberg, Can We Still Believe the Bible? An Evangelical Engagement with Contemporary Questions (Grand Rapids: Brazos, 2014); and Hank Hanegraaff, Has God Spoken? Memorable Proofs of the Bible’s Divine Inspiration (Nashville: Thomas Nelson, 2011).
  14. See Voddie Baucham, Expository Apologetics: Answering Objections with the Power of the Word (Wheaton, IL: Crossway, 2015).
  15. Dorothy L. Sayers, “The Dogma is the Drama,” The Whimsical Christian: 18 Essays (New York: MacMillan, 1978), 12.
  16. Sayers, “The Dogma is the Drama,” 13.
  17. See Craig L. Blomberg, “Jesus of Nazareth” in Groothuis, Christian Apologetics.
  18. See John R. W. Stott, Christ the Controversialist (Tyndale Press, 1970).
  19. See Groothuis, “In Defense of the Incarnation,” Christian Apologetics.
  20. See Groothuis, “The Resurrection of Jesus,” Christian Apologetics.
Share This