The Rationality of Christian Faith

A survey of the historical development of ‘Reformed Epistemology,’ tracing the ‘divine spark,’ the ‘divine seed,’ and the ‘sensus divinitatis (divine sense)’ toward developing a philosophical defense for the rationality of man’s belief in God.

Alvin Plantinga

One of the most important ideas introduced to Christian philosophy in the twentieth century was reformed epistemology, a thesis most notably propagated by renowned Christian philosopher Alvin Plantinga.  Reformed epistemology offers a powerful defense of the rationality of Christian faith against opponents who have attacked Christian belief as irrational or intellectually disreputable.  Plantinga develops a model that argues Christian belief does not need to be supported by evidentialist arguments or generally accepted premises to be warranted but instead suggests knowledge of God is plainly perceived in a basic way by those with a properly functioning sensus divinitatis. This sensus divinitatis, or divine sense, is a “disposition or set of dispositions to form theistic beliefs in various circumstances, in response to the sorts of conditions or stimuli that trigger the working of this sense of divinity.”[1]  Put another way, the sensus divinitatis is a “belief-producing process . . . [which] works under various conditions to produce beliefs about God.”[2]  This divine sense is not knowledge of God, but the natural capacity for a person to obtain knowledge of God.  By his own confession, Plantinga reveals this notion, which is a foundational piece of reformed epistemology, is adopted directly from the work of John Calvin.[3]  This article will make an examination of reformed epistemology, its dependence on the sensus divinitatis, and trace the historical development of this model.  This paper will argue that the divine sense, which lies at the heart of reformed epistemology, originated not in Christianity, but in Hellenistic philosophy.  To demonstrate this point, this article will examine the concepts prolepsis and the divine spark in Cicero’s works, will recount the Christian reformulation of these notions in the work of John Calvin, and then make an extended study of reformed epistemology’s dependence on the application of Calvin’s sensus divinitatis in the Aquinas/Calvin (A/C) Model which is central to this philosophical system.

Cicero, Prolepsis, and the Divine Spark


Considered to be “the greatest orator and Latin prose writer of all time,”[4] Cicero lived in the time of Julius Caesar and contributed a lasting influence on ethics in the West.  “Cicero champions the doctrine that humanity is a brotherhood that shares a divine spark and is cared for by a divine providence.”[5]  In his seminal work, On Obligations, he discusses the topics of prolepsis, preconception, a priori knowledge, natural law, human rights, and the divine spark.  For Cicero, the divine spark is what sets humans apart from the animals.  This glimmer of divinity is the foundation for “human fellowship [which] in its broadest sense unit[es] all men with each other.”[6]  Cicero is concerned primarily to develop a universal moral philosophy, and his interest in the divine spark is primarily as a ground for his notion of human moral obligations which operated as a historical precursor to the development of natural law and human rights.[7]

In undertaking an effort to interpret Epicurean theology, Cicero develops an epistemology that contends knowledge of the gods is inherent to all humanity.[8]  Cicero contends, “nature herself has imprinted a conception of [the gods] on the minds of all mankind.”[9]  This conception is a universally given “prolepsis” (or preconception), which is something “without which nothing can be understood or investigated or discussed.”[10]  In other words, this knowledge of divinity is a “prior notion,” and an “innate concept” that is “engraved,”[11] and universal within all people.  Cicero asks, “What nation or what tribe of men is there but possesses untaught some ‘preconception’ of the gods?”[12]  Cicero defends his position saying, “Those who have committed [an impious crime] . . . are not only unable to rest peacefully [afterward], but cannot even breathe without fear.”[13] Depravity, however, diminishes this divine light, and “under the corrupting influence of bad habits and beliefs, we . . . become infected with deceptions so varied that truth gives way to unreality.”[14]  In Cicero’s account, even those who would attempt to deny God’s existence could never fully escape what they inherently know to be true, which is that God exists.  Thus, belief in God being a universally shared belief among all people is sufficient proof that the belief must be true.[15]

Cicero gained the vocal admiration of a number historic Christian theologians.  “His doctrines were received and purified in the Christian tradition and they continue to inspire” Christian philosophers in the present day.[16]  Saint Augustine reports in the Confessions, that it was Cicero’s work that, at a young age, won the esteemed theologian to philosophy.[17]  Saint Ambrose, Bishop of Milan, made extensive references to Cicero within his work,[18] and Erasmus went so far as to say that his appreciation for Cicero’s stirred in him contempt toward educators who found nothing noteworthy in Cicero beyond the splendor of his language.[19]  John Calvin, in the first five chapters of the Institutes of the Christian Religion, turns to Cicero for far-reaching support in his theological writings, and, as will be demonstrated, employed Cicero’s notion of prolepsis and the spark of divinity in every man to pen his reflections on man’s natural knowledge of God.[20]

John Calvin and the Sensus Divinitatis

John Calvin

Largely recognized as a student of classical antiquity, “it is not difficult to gather the names of renowned scholars who are prepared to acknowledge John Calvin’s far-reaching indebtedness to humanism.”[21]  The famed sixteenth-century theologian showed a remarkable affinity for the writings of Cicero in the formulation of his biblical interpretation of the sense by which man comes knowledge of God.  Egil Grislis observes “several close parallels between the insights of Cicero and Calvin,”[22] and goes so far as to claim that Calvin’s argument is “essentially a restatement of Cicero’s insight.”[23]  Charles Partee is less certain of Calvin’s dependence on Cicero as the source of his ideas.  Because Cicero was thoroughly eclectic, it is instead possible that Calvin and Cicero both borrowed from a common source.  Partee agrees with Grislis, however, that “the parallels [between Cicero and Calvin] are clear.”[24]

Like Cicero, Calvin adopts the idea that there exists a universal “seed of religion” present within every individual that produces a ‘certain understanding of [God’s] divine majesty.’[25]  This seed is a type of knowledge of God’s existence, apart from Scripture, that can be perceived by all human beings.  This awareness of divinity, which Calvin describes as a naturally inborn instinct and disposition implanted by God, Calvin coined the sensus divinitatis. Edward Adams explains that, for Calvin, the sensus divinitatis is not merely an intuition but a cognitive intellectual consciousness of God the creator. [26]  Calvin further contends that even the most brutish people contain this seed, and this “sense of divinity inscribed in the hearts of all” cannot be “effaced.”[27]  Like Cicero, Calvin says that all people possess a “natural disposition,” and a “light of nature” that allows for knowledge of God, and “some conception of God is ever alive in all men’s minds.”[28]  Adopting the notion of prolepsis, Calvin claims that natural knowledge of God “is not a doctrine that must first be learned in school, but one of which each of us is master from his mother’s womb and which nature itself permits no one to forget, although many strive with every nerve to this end.”[29]  Again agreeing with Cicero, Calvin posits atheists never fully escape the very sense of God they strive so ardently to avoid.  “[Those] who deny that God exists . . . from time to time feel an inkling of what they desire not to believe,”[30] and “the worm of conscience, sharper than any cauterizing iron, gnaws away within.”[31]

While both Cicero and Calvin agree that divine prolepsis is the primary sense by which people come to the knowledge of God, they also “desire to pay attention to the additional evidence which can be gathered by use of empirical reason.”[32]  For example, Cicero writes, “Indeed, who is so witless that when he gazes up into heaven, he fails to see that gods exist, and imagines that chance is responsible for the creations of an intelligence so transcendent that scarce can the highest artistry to do justice?”[33]  Calvin agrees, “There are innumerable evidences both in heaven and on earth that declare [God’s] wonderful wisdom . . . which thrust themselves upon the sight of even the most untutored and ignorant persons, so that they cannot open their eyes without being compelled to witness them.”[34]  Ultimately Calvin does not go so far as to follow Cicero in making the claim that the universal preconception of God is sufficient proof for the existence of God, but Calvin instead asserts that God, having “implanted in all men a certain understanding of his divine majesty,” sufficiently “prevent[s] anyone from taking refuge in the pretense of ignorance.”[35]  In taking up Calvin’s sensus divinitatis, Alvin Plantinga takes a slightly different tact.  Where Calvin’s interest the sensus divinitatis is to provide answers to theological and epistemological questions about man’s acquisition of knowledge of God, Plantinga’s concern is to employ the divine sense for the apologetic purpose of defending Christian faith against those who would challenge the rationality of theistic belief.  In the sensus divinitatis, Plantinga finds the basis for identifying belief in God as a properly basic belief.

Alvin Plantinga and Reformed Epistemology

Embracing the thinking of Sigmund Freud and Karl Marx, twentieth-century assailants of theism staked the claim that regardless of whether Christian belief can be proven false, it is not possible that one can reasonably hold theistic beliefs.  These opponents of faith asserted that, while the claims of Christian belief cannot be categorically disproven, belief in God is without warrant and intellectually irresponsible.  Freud and Marx had differing opinions as to why Christians arrive at belief in God.  Freud contended theism is spawned in a subconscious desire people have for comfort in a cruel world.  He claimed Christians find this comfort via fantasy wish fulfillment.  Marx, on the other hand, argued that theistic belief is the result of cognitive-intellectual malfunction resulting from economic emotional distress.[36]  While Freud and Marx differ on how they understand Christians’ arrival at belief in God, the two writers share the conclusion that Christian belief is aimed at something other than truth.

Responding to these objections, Christian philosopher Alvin Plantinga begins by pointing out both Thomas Aquinas and John Calvin agree humans possess an innate sense of the divine.  Plantinga alerts readers, “Thomas Aquinas and John Calvin concur on the claim that there is a kind of natural knowledge of God (and anything on which Calvin and Aquinas are in accord is something to which we had better pay careful attention.)”[37]  Thomas Aquinas, the most famous classical proponent of natural theology, writes in the Summa Theologiae, “To know in a general and confused way that God exists is implanted in [mankind] by nature.”[38]  Rather than follow the natural theology approach, which attempts to produce an inferential argument that deduces God’s existence from independent evidence or premises, Plantinga suggests instead that some axiomatic beliefs are foundational and accepted apart from people’s lacking the ability to appeal to evidence to justify them.  Plantinga’s move here is monumental.  This argument that some knowledge is foundational posits that some beliefs are not produced or defended by rational deliberation.  That is, they do not appeal to more primitive beliefs or evidence to justify them, and they encounter no compelling evidence to suggest they are false. For example, perception, memory, and a priori beliefs fit this description.  These beliefs are properly basic. They are either self-evident or incorrigible – meaning one can believe them without possibly being proven wrong.[39]

Plantinga is convinced there is not sufficiently good evidence for belief in God in the way that evidentialism demands.  Thus, Plantinga abandons the evidential dependence of natural theology and turns his approach to foundationalism.  To do this, Plantinga employs Calvin’s sensus divinitatis, which he takes to be a belief-producing faculty, to make the case that justification and warrant for Christian belief as knowledge comes from the belief’s arising in a properly basic way.  In this sense, Christian belief arises from the reception of the sensus divinitatis and is foundational in that it is self-evident and does not arise from other prior beliefs.  Like other properly basic beliefs, knowledge of God’s presence in the world is intuitive, obvious, immediate, and non-inferential.

Plantinga further argues that Christian belief can be perfectly rational and sensible.  Christians violate no intellectual duties in holding their beliefs, and objections to the rationality of Christian belief necessarily depend on the assumption that Christian belief is false.[40]  Plantinga’s conclusion demands that any objection to the rationality of Christian belief requires the objector must first disprove the existence of God.  At the foundation of Plantinga’s model is the ‘sensus divinitatis.’

Where Calvin seems to think knowledge of God is innate “from the mother’s womb,” Plantinga makes a critical and controversial point of divergence.  Plantinga conceives of the sensus divinitatis not as knowledge itself, but as the cognitive faculty providing the ability to develop such knowledge.  Plantinga says, “What one has from one’s mother’s womb is not this knowledge of God, but a capacity for it.”[41]  The sensus divinitatis is the sensory system or organ in which a wide variety of circumstances trigger the disposition to form the occasion on which beliefs about God arise.  People do not have these beliefs embedded within them inherently, nor do they choose to have them, but instead, have the sense to develop them when this faculty encounters circumstances.[42]  For Plantinga, the sensus divinitatis takes the circumstances as input and issues theistic beliefs as output.  “The sensus divinitatis resembles perception, memory, and a priori belief,”[43] and in the same way that being appeared to occasions particular beliefs that are properly basic, and not accepted on the evidential basis of other propositions, so it is with beliefs arising from the sensus divinitatis.[44]

Granting the notion that beliefs arising from the sensus divinitatis are properly basic, Plantinga asserts that “there is no sensible challenge to the rationality or rational justification or warrant of Christian belief that is not also a challenge to its truth.”[45]  And thus, Plantinga explains the sensus divinitatis’ foundational role in reformed epistemology.

The sensus divinitatis is a belief-producing faculty (or power, or mechanism) that under the right conditions produces belief that isn’t evidentially based on other beliefs.  On this model our cognitive faculties have been designed and created by God’ the design place, therefore, is a design plan in the literal and paradigmatic sense.  It is a blueprint or plan for our ways of functioning, and it has been developed and instituted by a conscious, intelligent agent.  The purpose of the sensus divinitatis is to enable us to have true beliefs about God; when it functions properly, it ordinarily does produce true beliefs about God.  These beliefs, therefore, meet the conditions of warrant; if the beliefs produced are strong enough, then they constitute knowledge.[46]

This is the central thesis of the reception knowledge of God in the reformed epistemology model.  “God has so constructed us that we naturally form the belief in his existence under appropriate circumstances, just as we do the belief in perceptual objects, the reality of the past, and so forth.  Hence, belief in God is among the deliverances of reason, not faith.”[47]

Reformed epistemology continues by next explaining that the sensus divinitatis has been marred by sin.  Plantinga explains, “Original sin involves both intellect and will; it is both cognitive and . . . primarily an affective disorder or malfunction.”[48]  Sin is like a disease which affects the receptive organ of faith, the sensus divinitatis.  Much like the way in which disease affects other organs, sin is a degenerative disorder that corrupts the cognitive function of both intellection and affections, confusing human loves and hates, distorting human understanding, and directing affections toward the wrong objects.[49]  Thus, human affections, corrupted by sin, no longer work in accord with God’s original design plan,[50] and while the affected individual sees what is right, he prefers what is wrong.  However, while this corrupted state provides a “fertile field for ambiguity and self-deception,” sin merely corrupts the sensus divinitatis but does not completely obliterate it.[51]

What is needed for Christian belief is a properly functioning sensus divinitatis.  Enter the redemptive gospel of Jesus and the regenerating work of the Holy Spirit. In Plantinga’s model, it is the Holy Spirit who is responsible for the reparative work of the divine sense in bringing about faith in believers.  The activity of the Holy Spirit involves means by which belief is regularly produced in regular ways. In this, the cognitive process by which the Spirit instigates the perception of faith “resembles memory, perception, reason, sympathy, induction, and other more standard belief-producing processes.”[52]  Faith often has the phenomenology that goes with suddenly having eyes to see something to be true,[53] but while Christian beliefs may contain excellent arguments, Christian belief, as arises from the sensus divinitatis, is not accepted based on propositional logic, but is the result of genuine religious experience.[54]  More than propositional belief, faith requires the right affections.  “The demons believe and they shudder” (James 2:19), but the demons do not have faith. The person with faith has not only the right beliefs but also the right affections.  “Conversion, therefore, is fundamentally a turning of the will, a healing of the disorder of affection that afflicts us.”[55]  As Jonathan Edwards wrote, “True religion, in great part, consists in holy affections,”[56] and Thomas Aquinas explained, “The Holy Spirit makes us lovers of God.”[57]  Thus, the restorative work of the Holy Spirit is not just one that enables a person to rightly perceive of God but also heals the disorder of affection that afflicts mankind.[58]  By the reparative work of the Holy Spirit, the person comes to see the great truth of the gospel and hear Christ’s voice in His Word.  In this way, the truths of the gospel and the Scripture are properly basic for believers because they are self-authenticating, and do not receive their warrant on the evidential basis of other propositions.[59]

Reformed epistemology allows that “the full panoply of Christian beliefs” may be properly basic if God exists.  In Plantinga’s Extended Aquinas/Calvin Model, believers need not justify their beliefs by evidence or argument because they have warrant for their Christian beliefs in the basic way.  God has constituted people such that they naturally come to believe in Christ when placed in the appropriate circumstances through properly functioning cognitive faculties repaired by the work of the Holy Spirit.  These cognitive faculties inherently possess a natural ability (sensus divinitatis) to perceive of the divine when operating as God designed (free from the corruption and brokenness resulting from sin).  Hence, God is perceived by the natural senses, known in a properly basic way, and faith is among the deliverances of reason.

Consequently, “Plantinga drops a bomb into mainstream epistemology by proposing . . . that one’s cognitive faculties are functioning properly only if they are functioning as God designed them to. . . . God has so constituted us that we naturally form [belief in God’s existence] under certain circumstances; since the belief is thus formed by properly functioning cognitive faculties in an appropriate environment.”[60]  This flips the assault of the atheists on its head.  On Plantinga’s account, the argument of Freud and Marx that Christianity is irrational and aimed at something other than truth becomes a valid conclusion only on the assumption that God does not exist.  Conversely, in the case that God does in fact exist, it is Freud, Marx, and the atheists whose beliefs are irrational.  Thus, Christian belief is warranted in so far as God exists.  This disallows the antitheist to contend that Christian belief is irrational, unjustified, or unwarranted; and leaves it to the atheist to disprove the existence of God.


Reformed epistemology is among the most important Christian philosophical works of the last century and has significantly undercut the arguments of philosophers who attempt to brand Christian belief as unwarranted.  This modern defense of Christian faith against the most powerful assaults of the twentieth century rests on reformed epistemology’s diffusion of their claims.  Plantinga’s suggestion that God has implanted mechanisms which could produce a powerful warrant for belief in God through a natural sense of the divine, strengthened and restored by the testimony of the Holy Spirit, is dependent on Calvin’s contributing conception of the sensus divinitatis.  At the same time, Calvin, and Christians, in general, owe a great deal of appreciation to the pagan philosopher, Cicero, and his eclectic dependence on the Epicureans, for providing Christianity with foundational aspects of this core epistemological concept upon which the powerful defense of warranted Christian belief is built.

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Chad W. Hussey is an average Jesus loving iconoclastic non-conformist neighborhood hope dealer from Houston Texas – a husband, father, preacher, and Master of Divinity student at The Southern Baptist Theological Seminary.





[1]Alvin Plantinga, Warranted Christian Belief (New York:  Oxford University Press, 2000), 173.

[2]Alvin Plantinga, Knowledge and Christian Belief (Grand Rapids, MI:  Eerdmans Publishing, 2015), 45.

[3]Plantinga, Knowledge, 33.

[4]Thomas P. Scheck, “Humanitas in Cicero’s Moral Philosophy and its Christian Reception,” in Ave Maria Law Review (2012), 405.

[5]Ibid, 406.

[6]Cicero, On Obligations, Book I trans. P. G. Walsh (Oxford University Press, 2000), 11-17.

[7]Cicero, On Obligations, 49, supra note 3.

[8]Egil Grislis, “Calvin’s Use of Cicero in the Institutes I:1-5 – A Case Study in Theological Method,” in Archiv fiir Reformationsgeshichte, 62/1 (1971), 5.

[9]Cicero quoted in The Loeb Classical Library I. XVI (London:  Harvard University Press, 1933), 43.

[10]Ibid, 44.


[12]Loeb I. XXIII, 65.

[13]Loeb I. XVI, 43.

[14]Loeb III. I, 2, 224-226.

[15]Loeb I. XVII, 44, 46.

[16]Scheck, “Humanitas,” 406.

[17]St. Augustine, Confessions trans. Edward B. Pusey, Book III (P. F. Collier & Son, 1909), 134.

[18]Harald Hagendahl, Latin Fathers and the Classics (1958), 348-381.

[19]Desiderius Erasmus, “Letter from Desiderius Erasmus to Johann von Vlatten (1523),” in 10 Collected Works of Erasmus trans. R. A. B. Mynors & Aleander Dalzell (University of Toronto Press, 1992), 96-98.

[20]Grislis, “Calvin’s Use of Cicero,” 5-37.

[21]Grislis, “Calvin’s Use of Cicero,” 5.


[23]Ibid, 13.

[24]Charles Partee, Calvin and Classical Philosophy (Westminster:  John Knox Press, 2005), 43.

[25]John Calvin, Institutes of the Christian Religion trans. Henry Beveridge (Peabody, MA: Hendrickson Publishers, 2008), I.iii.3.

[26]Calvin, Institutes, I.iii.3.

[27]Ibid, I.iv.1, I.iii.3.

[28]Edward Adams, “Calvin’s view of Natural Knowledge of God” in International Journal of Systematic Theology, 3 (November, 2001), 284.

[29]Calvin, Institutes, I.iii.3.

[30]Ibid, I.iii.2.

[31]Ibid, I.iii.3.

[32]Grislis, “Calvin’s Use of Cicero,” 8.

[33]Loeb IX, 19, 338.

[34]Calvin, Institutes, I.V.2.

[35]Ibid, I.iii.1.

[36]Plantinga, Warranted Christian Belief, 170.


[38]St. Thomas Aquinas, Summa Theologiae (Cambridge:  Cambridge University Press, 2006), I, q. 2.a.1, ad 1.

[39]Alvin Plantinga, Faith and Rationality (London:  Notre Dame, 1983), 58-59.

[40]Plantinga, Knowledge, ix.

[41]Plantinga, Warranted Christian Belief, 173.

[42]Ibid, 172.

[43]Ibid, 175.


[45]Ibid, 169.

[46]Plantinga, Warranted Christian Belief, 179.

[47]William Lane Craig, Reasonable Faith:  Christian Truth and Apologetics 3rd ed. (Wheaton, IL:  Crossway, 2008), 40.

[48]Plantinga, Knowledge, 49.


[50]Ibid, 50.

[51]Plantinga, Knowledge, 51.

[52]Ibid, 63.

[53]Ibid, 61.

[54]Ibid, 64.

[55]Ibid, 74.

[56]Jonathan Edwards, A Treatise Concerning Religious Affections ed. John E. Smith (New Haven, Yale University Press, 1959), 95.

[57]St. Thomas Aquinas, Summa Contra Gentiles trans. Charles O’Neil (Notre Dame:  University of Notre Dame Press, 1975), IV.21-22.

[58]Plantinga, Knowledge, 74.

[59]Plantinga, Warranted Christian Belief, 261-262.

[60]Craig, Reasonable Faith, 40.

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