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Reasoning God’s Existence from First Principles

Read in:

17 minutes
Reasoning God’s Existence from First Principles


As skepticism and secularism gain more traction in our world today, establishing a rational defense of belief in God and Jesus Christ has become increasingly important. The principles of first principles reasoning, foundational to philosophy and science alike, offer a compelling avenue to ground such an argument providing convincing reasoning for this belief. This article draws from the wisdom and arguments of renowned apologists like Norm Geisler, J. Warner Wallace, Greg Koukl, Lee Strobel, Josh McDowell, C.S. Lewis, Tim Keller, Hugh Ross, as well as the timeless truths of the Word of God itself. By establishing our discussion in these first principles, we demonstrate not just the rationality, but the profound necessity of believing in God as the best explanation for the existence of the universe around us as well as for our own existence.

Let’s proceed with understanding first principles reasoning and its application in establishing belief in God and Jesus.

Understanding First Principles Reasoning

First principles reasoning is a method of inquiry that breaks down complex problems into their most basic, foundational elements. It seeks to bypass assumptions, conventions, and received wisdom, instead starting from the ground up to construct knowledge and understanding. This approach is deeply rooted in the philosophical tradition, tracing back to Aristotle who advocated for understanding complex subjects by discerning their fundamental principles. In the realm of theology, first principles reasoning allows us to approach the existence of God and the truth of Christianity not as matters of blind faith but as hypotheses that can be examined and reasoned about.

The significance of this approach lies in its ability to clear the clutter of preconceived notions and cultural biases, enabling a pure, unadulterated search for truth. It’s the intellectual equivalent of starting with a clean slate, building one’s understanding piece by piece from the most basic truths. This method has led to revolutionary breakthroughs in science and philosophy, from Newton’s laws of motion to Descartes’ cogito ergo sum (“I think, therefore I am”). Similarly, when applied to theology, first principles reasoning opens up a fresh, rigorous avenue for exploring the existence of God and the historical reality of Jesus Christ.

Arguments for a Creator from First Principles

On what first principles can we reason the existence of an intelligence which we can say has the attributes we would expect in a creative, a designing and moral law giving divine being?

Cosmological Argument: At its core, the cosmological argument starts from the first principle that everything that begins to exist has a cause. The universe, having a beginning, must also have a cause. This line of reasoning is not new; it echoes through the works of philosophers like Aquinas and Al-Ghazali and is robustly defended today by apologists like William Lane Craig. The argument points beyond the universe to a cause that is itself uncaused—traditionally understood to be God. This uncaused cause is posited to be necessary, uncaused, timeless, spaceless, immaterial, powerful, and personal – characteristics fitting the conception of a Creator God.

Galaxy as part of God's cosmos

Teleological Argument: The fine-tuning of the universe for life is another point of discussion. Scientists like Hugh Ross argue that the precise conditions necessary for life to exist point to a universe that is not accidental but purposefully made. The constants of the universe (gravity, electromagnetic force, etc.) are so finely tuned that their alteration by even a hair’s breadth would render the universe lifeless. This suggests a designer who calibrated the universe’s conditions for life—a powerful argument for the existence of an intelligent Creator.

Moral Argument: C.S. Lewis famously articulated the moral argument for God’s existence, suggesting that our universal sense of right and wrong points to a moral lawgiver. This argument, further expanded by Tim Keller, posits that the presence of objective moral values and duties indicates a source beyond humanity. These moral laws imply a moral lawmaker, which we identify as God. This line of reasoning supports the idea that morality is not a human invention but a divine imprint on humanity.

Absolutely, the argument from specified complex information found in biological systems like DNA is another powerful evidence for an intelligent designer behind life. Here’s how I would articulate that line of reasoning:

Argument from Biological Information: When we look at even the tiniest living cell, we are immediately struck by the incredible complexity and specified information encoded within. DNA itself is an information storage marvel – chains of precisely ordered chemical letters that spell out detailed instructions for building all life. Beyond just data, it’s an operating program of unfathomable complexity.

As molecular biologists have mapped the inner workings of the cell, they uncover system after system of interdependent, nano-scale molecular machines and factories processing information, materials and energy with a coordination that boggles the mind. Specified complexity on that scale defies any notion of random, undirected processes.

This is something even dogmatic atheists like Richard Dawkins have tacitly acknowledged. As he said, “Biology is the study of complicated things that give the appearance of having been designed for a purpose.” That appearance is not just surface-level but reflects deep information-rich systems that scream “designed” by an intellect not inferior to our own.

Just as we universally infer intelligence behind a deep, multilayered computer code or hieroglyphics – so too the encyclopedic information storage and processing we find in life points compellingly to a brilliant mind behind it all. An intentional, information-rich architecture. Not randomness and chaos, but specified, coded instructions befitting the work of a supreme intelligence. As renowned philosopher of science Stephen Meyer argues, Intelligent Design provides the best explanation for the undeniable evidence of information defining life as we know it.

DNA as the code in the cell and the finger print of God

These arguments, grounded in first principles reasoning, offer a compelling case for the existence of a creator, a designing intelligence and moral law giver. They bypass the superficial layers of skepticism, inviting a deeper inquiry into the foundations of reality, morality, and the cosmos itself.  Understanding this just who this creator, a designing intelligence and moral law giver is the focus of the next section.

Who is this Creator, Designer, Moral Law Giver?

While the philosophical and scientific arguments lay a robust foundation for the existence of an intelligent Creator, designer, and moral lawgiver, they don’t answer the crucial query – just who or what is this divine being? The arguments point unavoidably to an immensely powerful, superintelligent, and transcendent Mind. But has this Mind made itself known to humanity more directly?

This is where the historical investigation of the world’s religious traditions becomes vital. If there is a Creator who fashioned the intricacies of the universe and imbued humanity with moral awareness, surely such a being would not remain utterly inscrutable. We should expect some level of divine revelation and interaction with the created order.

Among the major faiths, Judaism and Christianity make some distinct claims about the nature and actions of the Creator that align remarkably with the philosophical arguments and merit closer inspection:

Firstly, the concept of God as an eternal, transcendent, all-powerful, and personal being agrees with the very attributes we deduced from first principles about the nature of the uncaused First Cause. This rules out pantheistic or impersonal conceptions of the divine.

Secondly, both traditions ground their origins in historical narratives depicting this Creator God as actively involved in the physical universe and in the lives of people. The accounts don’t just philosophize about God’s existence, but claim to record actual interventions, revelations, and miracles by which God made Himself undeniably known.

No other major religion makes such specific claims about God’s creator actions being historically instantiated and documented in the visible world. The Judeo-Christian faiths stake everything on the purported factuality of these divine acts of self-revelation.

Additionally, the moral arguments resonate powerfully with the unique Judeo-Christian understanding of God as the objective source and standard for our shared ethical intuitions about good and evil, right and wrong.

So, while other religions affirm a Creator in some sense, the specific claims of Judaism and Christianity regrading God’s eternal nature, His active self-revelation in history, and His moral attributes align most compellingly with the philosophical reasoning we have embarked upon. From the very origins recounted in the Torah and Old Testament, we encounter a deity consistent with the first principles deductions – an uncaused, transcendent, personal Being who crafts the cosmos and humanity with intentionality. This same God then proceeds to repeatedly manifest and reveal himself in history through prophets, visions, miracles and climactically through the extraordinary figure of Jesus Christ.

While Judaism roots its understanding of God in those Old Testament foundations, Christianity hinges on the proposition that in the person of Jesus, the Creator God became incarnate. It’s a stunning, eternal act of divine self-revelation. 

First principles reasoning can build a powerful philosophical case for an intelligent Creator that we have identified as the God of the Universe. Christian teaching and tradition purports to give us something more – an up-close encounter with that very same Creator God in the form of Jesus Christ. The historic claims and evidence surrounding this Jesus then become the pivotal issue for assessing the rationality of the Christian worldview.

The Historical Jesus: Evidence and Reasoning

The historicity of Jesus Christ and the veracity of the events described in the Gospels are of course foundational to Christianity. This section draws on the investigative works of apologists like Lee Strobel, J. Warner Wallace, and the scholarly insights of Gary Habermas and Josh McDowell to present a reasoned case for the historical Jesus.

Reliability of the Gospel Accounts: The Gospels are not mere religious texts but historical documents that provide eyewitness accounts of Jesus’ life, death, and resurrection. Critics like J. Warner Wallace, a former cold-case detective, approach the Gospels with the same scrutiny applied to forensic evidence and find them reliable. This reliability is supported by the inclusion of embarrassing or counterproductive stories in the Gospels, early dating of the writings near the events they describe, and corroboration by non-Christian sources.

The Embarrassment of the Cross: One of the most historically compelling aspects of the gospel narratives about Jesus is the portrayal of the humiliating circumstances surrounding his death. Depicting the death of Jesus through execution in one of the cruelest, most shameful ways imaginable in ancient world was not a good way to attract followers.  Crucifixion was a punishment reserved for the lowest criminals and rebels against Roman rule. It was designed to maximize torture, humiliation, and public scorn.

The cross was an unusual symbol of triumph during the Roman empire

Yet, the original gospel writers did not censor or reframe this embarrassing denouement to Jesus’ life, which actively scandalized their Jewish audience. This “stumbling block” of the cross flew in the face of any political or religious motivations they could have had to exalt Jesus’ image. By including such an embarrassing climax instead of a glorious victorious conclusion, the biblical authors lent significant historical credibility to their accounts.

The Case for the Resurrection: Perhaps the most pivotal event in Christian doctrine, the resurrection of Jesus defines the Christian faith. The minimal facts approach, advocated by Gary Habermas, argues for the resurrection based on facts agreed upon by the majority of scholars, both skeptical and believing. These include the empty tomb, the post-mortem appearances of Jesus, and the sudden shift in the disciples’ behavior from fear to bold proclamation of the Gospel. The best explanation for these facts, argued by Lee Strobel and others, is that Jesus truly rose from the dead.

Non-Christian Historical Evidence: Historical references to Jesus and early Christians by Roman and Jewish historians like Tacitus and Josephus add an extra layer of credibility. These accounts, corroborate the existence of Jesus and the early Christians’ belief in His divinity and resurrection. 

Through a combination of internal consistency, external corroboration, and logical inference, the historical case for Jesus as presented in the Gospels emerges not just as a matter of faith but as a plausible historical reality.

Rational Faith: Beyond Blind Belief

Faith in God and Jesus Christ is often misconstrued as blind belief, devoid of evidence or reason. However, figures like C.S. Lewis and Tim Keller argue for a conception of faith that is deeply rational, rooted in evidence and reason, and complemented by personal experience and the work of the Holy Spirit.

Faith and Reason as Complementary: The notion of religious faith is often misconstrued as blind, anti-rational belief. But thinkers like C.S. Lewis and Tim Keller have argued compellingly that authentic Christian faith is deeply rooted in reason and evidence.

Lewis portrayed such faith not as an irrational leap into darkness, but as a step further into the light of rational confidence. As he put it, Christian faith relies on reason to examine the evidence, but then makes a voluntary commitment to the perceived Truth.

Keller elaborates that faith isn’t about shelving one’s intellect but rather utilizing resources like philosophy and investigation. It then goes beyond purely experinced to entrust ourselves to what has excellent reasons for being true – akin to how we rely on friends beyond what can be exhaustively proven.

So, while Christian faith involves truths beyond strict empirical proof, it isn’t at odds with reason. At its best, it embraces logic and evidence as vital partners in the journey towards ultimate truth. Faith and reason are seen as complementary, not contradictory pathways.

Role of the Holy Spirit: The rational arguments and historical evidence can lead one to an intellectual understanding of Christian truth claims. However, Christianity also speaks of a personal, experiential dimension that brings those beliefs into the realm of lived reality – the work of the Holy Spirit.

Both Lewis and Keller affirm that while reason is vital, there comes a point where the mind must go beyond an experiential encounter. The Holy Spirit facilitates this transition from understanding to embodied faith and transformation.

It’s not viewed as an irrational step disconnected from evidence, but as the fulfillment of reason’s quest. The Spirit confirms and illuminates truth in a profound way, making it real and tangible within the believer. Logic and history lay the groundwork, but the Spirit brings alive and verifies that truth.

We are reminded of God through His Spirit

Lewis described it as the Spirit taking abstract, intellectual understanding and turning it into a profound, living spiritual reality made real within the believer. Keller echoes this, stating that the Spirit’s work allows Christianity to transcend being a mere concept and instead be experienced as an authentic, transformative truth.

Rational faith, then, is not an oxymoron but a harmonious blending of reason and revelation, evidence, and experience. It acknowledges the limits of human understanding while embracing the fullness of divine revelation.

The Bible and First Principles Reasoning

The Bible, far from discouraging the use of reason, encourages believers to engage their minds fully in their faith. Apologists like Greg Koukl and Hugh Ross point out that Scripture endorses a reasoned faith, one that stands up to scrutiny and questioning.

Scriptural Endorsement of Reason: Rather than discouraging the use of intellect, the Bible endorses and even commands believers to vigorously engage their minds in understanding their faith. Scripture doesn’t present truth as anti-rational, but as something to be grappled with, questioned, and defended through rigorous reasoning.

The book of Proverbs extols the virtues of wisdom, understanding, and the diligent application of the mind. It states, “The mind of the prudent acquires knowledge” (Proverbs 18:15) and “The purposes of a person’s heart are deep waters, but one who has insight draws them out” (Proverbs 20:5). These passages celebrate intellectual striving after truth.

The prophets also display a willingness to argue, reason, and make their case through evidence and logic. Isaiah challenges idolaters, “Present your case…set forth your arguments” (Isaiah 41:21). He later invites open dispute – “Come now, let us reason together” (Isaiah 1:18). The God of Scripture welcomes questions and intellectual scrutiny.

Jesus himself was known as a skillful debater who aptly fielded challenges from religious scholars of his day through nuanced reasoning and counter-questioning. The apostle Paul likewise engaged philosophers on Mars Hill through philosophical arguments about the nature of God. We find that the biblical narrative consistently endorses believers developing a coherent, rationalized understanding able to withstand scrutiny. It depicts God’s truth as something the mind can grapple with and apprehend through vigorous use of reason.

Biblical Consistency with Science and History: Scholars like Hugh Ross have demonstrated how the Bible aligns with scientific understanding and historical evidence, suggesting that its truths are not only spiritually relevant but also intellectually credible. The Bible’s narratives, prophecies, and teachings, when examined through the lens of reason and evidence, reveal a coherent, consistent message that withstands critical scrutiny.

Through these examples, it’s clear that the Bible advocates for a faith that engages both the heart and the mind, embodying the principles of rational inquiry and belief.


Establishing belief in God and by extension Jesus Christ through first principles reasoning is not only rational but provides the most coherent and compelling explanation for the universe, morality, and human value and experience. Drawing from the works of esteemed apologists and the profound truths of Scripture, we’ve explored how faith and reason are not adversaries but allies in the search for truth. This approach invites believers and skeptics alike to consider the evidence, engage their intellect, and open their hearts to the transformative power of faith. In doing so, Christianity emerges not as a blind leap into the dark but as a reasoned step into the light.

This exploration encourages further inquiry and reflection, inviting all to delve deeper into the rich intellectual tradition of Christian apologetics and the life-changing message of the Gospel. Whether through personal study, discussion groups, or engaging with the vast array of resources available from the apologists mentioned, there’s a wealth of knowledge and insight waiting to enrich your understanding and strengthen your faith.

Further Reading and Resources:

Craig, William Lane. Reasonable Faith: Christian Truth and Apologetics. 3rd ed., Crossway, 2008. This book provides a comprehensive defense of the truth of the Christian faith, covering arguments for the existence of God, the historicity of Jesus, and the rationality of Christian belief.

Lewis, C.S. Mere Christianity. HarperCollins, 1952. A classic work that explores Christian belief from the ground up, addressing common questions and objections and presenting a compelling case for the Christian faith.

Strobel, Lee. The Case for Christ: A Journalist’s Personal Investigation of the Evidence for Jesus. Zondervan, 1998. Strobel, a former atheist and investigative journalist, examines the evidence for Jesus Christ and presents his findings in a way that is both accessible and compelling.

Keller, Timothy. The Reason for God: Belief in an Age of Skepticism. Riverhead Books, 2008. Keller addresses common doubts and objections to Christianity and makes a reasoned case for faith in God, drawing on literature, philosophy, reason, and real-life conversations.

McDowell, Josh, and Sean McDowell. Evidence That Demands a Verdict: Life-Changing Truth for a Skeptical World. Updated ed., Thomas Nelson, 2017. This updated classic provides thorough research and evidence supporting the claims of Christianity, addressing questions about the reliability of the Bible, the historicity of Jesus, and more.