Natural Law: Preparation for the Gospel

In prior articles, I have demonstrate the confessional Lutheran view that natural law shows all people basic truths that are foundational for the Gospel: (1) the existence of God, (2) the moral law, (3) original sin, (4) the moral order, and (5) the immortality of the soul.

Collectively, these natural building blocks show humanity’s urgent need for the Gospel. Due to original sin, even our best actions violate the moral law, building up judgment in this life and the next. So all people need the radical forgiveness procured by God’s Son, who paid the moral penalty in our place.

This understanding did not begin with the Lutheran Reformers, though. By examining the writings of early Church Fathers, we see how natural law, from the beginning, has provided a bridge from human reason to divine revelation. Natural law testifies to the universal moral order inscribed by God on the human conscience, discernible through reason. Though dimmed by the Fall, this unwritten law persists as a witness to Divine purity, exposing our inability to enter heaven without forgiveness.

This article examines the insights of Justin Martyr, Irenaeus of Lyons, Clement of Alexandria, Tertullian, Origen, Eusebius of Caesarea, and Augustine of Hippo. They confirm that the Lutheran Reformers did not blaze a new trail, but built on the insights of devout early Christians.

Justin Martyr (100–165 AD)

Justin Martyr confronted a Hellenistic world steeped in philosophy. He framed natural law as "seeds of the Logos" embedded in creation, germinating in the minds of serious pagans through reason, preparing them for Christ.

Justin argued that the best Greek philosophers recognized God as the ultimate Creator who "produced and arranged [all things] into a world," as evidenced by their doctrines aligning with Plato's teachings on divine creation.[i] These thinkers elaborated truths about God and humanity by "finding and contemplating some part of the Logos.”[ii] Philosophers like Socrates exhorted others to "become acquainted with the God who was to them unknown, by means of the investigation of reason," acknowledging Him as the "Father and Maker of all."[iii]

Many Greeks grasped God's omnipotence, affirming that "with God nothing is impossible," particularly in contexts of soul immortality and resurrection.[iv] Plato recognized that "by the word of God the whole world was made" from shapeless matter, highlighting God's supreme role in forming the universe.[v]

God created humans with rational faculties for moral decision-making, rendering us inexcusable for wrongdoing. "In the beginning He made the human race with the power of thought and of choosing the truth and doing right, so that all men are without excuse before God; for they have been born rational and contemplative."[vi]

Bad motives such as selective benevolence are prohibited, because genuine goodness requires impartial love. "For not even when a man does good to his children and offspring, does one call him a good man; for even the most savage of the wild beasts do so, and indeed willingly endure death, if need be, for the sake of their cubs. But if a man were to perform the same acts on behalf of his slaves, that man would justly be called good."[vii] 

Greek philosophers recognized a permanent moral order involving post-death reward and punishment, where "the souls of the wicked . . . are punished, and . . . those of the good . . . spend a blessed existence."[viii] Thus, "sensation remains to all who have ever lived, and eternal punishment is laid up” for the wicked.[ix]

Divine justice ensures consequences for immoral acts. "[I]t is alike impossible for the wicked, the covetous, the conspirator, and for the virtuous, to escape the notice of God, and that each man goes to everlasting punishment or salvation according to the value of his actions."[x]

While many philosophers grasped these problems, Justin emphasized that restoration is only addressed in Christ, who "became man for our sakes, that becoming a partaker of our sufferings, He might also bring us healing," fulfilling what pagan wisdom could only partially discern.[xi]

Irenaeus of Lyons (130–202 AD)

Irenaeus explained natural law as universal precepts about God and morality, inscribed at creation and preparing humanity for the Gospel.

Natural law’s moral requirements confirm the moral law in Scripture. “Inasmuch, then, as all natural precepts are common to us and to [the Jews], they had in them indeed the beginning and origin; but in us they have received growth and completion. For [the requirements] to yield assent to [God], and to follow His Word, and to [love] Him above all, and one’s neighbor as one’s self . . . do reveal one and the same God.”[xii]

Natural law was sufficient pre-Fall, but now requires reinforcement from written Law. “At first God deemed it sufficient to inscribe the natural law, or the Decalogue, upon the hearts of men; but afterwards he found it necessary to bridle it” with written commandments.[xiii]

Irenaeus wrote that God's mighty "invisible essence" confers on all a “profound mental intuition and perception of His most powerful, yea, omnipotent greatness," confirming that “there is one God, the Lord of all."[xiv] God's "providence over all things" acquaints governed beings with their ruler and moves "certain of the Gentiles," less addicted to sensual allurements and idols, "being moved, though but slightly, by His providence," to recognize the universe's Maker as "the Father, who exercises a providence over all things, and arranges the affairs of our world."[xv] Through "the creation itself, the Logos reveals God the Creator," and the formation of man discloses "the Artificer who formed him," addressing "all men in the same manner."[xvi]

Christ is "the physician of the sick" who calls all people to recovery by "undergoing a great change and reversal of their former mode of living" from sinful paths burdened by ignorance, which is "driven out by knowledge."[xvii]

Christ paid for humanity's collective death stemming from Adam's transgression, since all have "become death's debtors."[xviii] Those who still choose to "depart from God" invite "separation from God" which "is death," along with "the loss of all the benefits which He has in store."[xix]

Clement of Alexandria (150–215 AD)

Clement of Alexandria viewed natural law as a unified rational moral order, training the soul in virtue, restraining sin, and cultivating piety, much like the Mosaic Law prepared the Hebrews for Christ.

Philosophy, based on natural law, was a divine schoolmaster for Gentiles, making the Hellenic mind receptive to the Gospel. “[P]hilosophy was given to the Greeks directly and primarily, till the Lord should call the Greeks. For this was a schoolmaster to bring 'the Hellenic mind,' as the law, the Hebrews, 'to Christ.'"[xx]

Natural law, developed by sound philosophy, convicts of divine providence and truth, preparing the soul for the Gospel’s complete revelation. “The philosophy which is in accordance with divine tradition establishes and confirms providence.”[xxi] “The barbarian and Hellenic philosophy have torn off a fragment of eternal truth.”[xxii]

Natural law is an innate moral guide, convincing all people to honor their Maker. “The law of nature, which is common to all mankind, calls us to worship the one God who made heaven and earth.”[xxiii]

The law of nature is the same as the moral law of Scripture. "Whether, then, it be the law which is connate and natural, or that given afterwards, which is meant, it is certainly of God; and both the law of nature and that of instruction are one."[xxiv]

Clement viewed the law of nature as God’s foundational moral guide, convicting those who violate it through acts "contrary to nature," such as unnatural lusts which "nature itself" prohibits.[xxv] This natural law is reinforced by the conscience, which internally torments sinners, as in the case of the adulterer who muses in his soul, "'Who sees me? darkness is around me, and the walls are my covering, and no one sees my sins. Why do I fear lest the Highest will remember?'" yet finds himself "tormented by conscience" and "hurries to repentance" upon exposure.[xxvi]

Sin arises fundamentally from "disobedience in reference to reason," which he identified as "the generating cause of sin," manifesting in core passions such as "lust, as desire disobedient to reason; fear, as weakness disobedient to reason; pleasure, as an elation of the spirit disobedient to reason."[xxvii] In contrast, the divinely implanted rational faculty enables virtue, which is "a state of the soul rendered harmonious by reason in respect to the whole life," where "philosophy itself is pronounced to be the cultivation of right reason" to align human actions with the divine order.[xxviii]

Clement argued that the law of nature, reinforced by human reason, convicts all people of sin by instilling an awareness that one must "believe that to which he was addicted to be sin" to abandon it, revealing the universal need for forgiveness to avert "punishment . . . impending over the transgressor."[xxix]

"Let us therefore repent, and pass from ignorance to knowledge, from foolishness to wisdom, from licentiousness to self-restraint, from unrighteousness to righteousness, from godlessness to God."[xxx]

Tertullian (155–240 AD)

Tertullian anchored natural law in creation’s moral order, portraying it as an unwritten, universal precept given to Adam, embodying divine wisdom in embryonic form. "[B]efore the Law of Moses, written in stone tables, I contend that there was a law unwritten, which was habitually understood naturally.”[xxxi]

Natural law binds all humanity, not just those with the Scriptures. “For why should God . . . be believed to have given a law through Moses to one people, and not be said to have assigned it to all nations? . . . For in the beginning of the world He gave to Adam himself and Eve a law . . . which law had continued enough for them, had it been kept. For in this law given to Adam we recognize in embryo all the precepts which afterwards sprouted forth when given through Moses; that is, You shall love the Lord your God. . . .You shall love your neighbor as yourself.”[xxxii]

Every soul has an innate knowledge of God, morality and judgment. "The soul has descended from heaven, not just on the Latins and the Greeks. One humanity comprises all races … The summons of God’s judgment is everywhere. The awareness of death is everywhere and the testimony of the soul is everywhere."[xxxiii]

The soul’s knowledge of God is reinforced by the external creation. "Would you have the proof from the works of His hands, so numerous and so great, which both contain you and sustain you, which minister at once to your enjoyment, and strike you with awe; or would you rather have it from the testimony of the soul itself?"[xxxiv]

The soul’s awareness of its sin shows the need for repentance and forgiveness to escape divine judgment. “Man’s soul, though bearing the divine law within, is stained by sin, and needs the cleansing of repentance and the grace of Christ’s forgiveness, lest it perish under divine judgment.”[xxxv]

Even immoral motives are subject to divine punishment, because natural law reveals God’s omniscience and justice, demanding accountability. "For if human finitude judges only sins of deed, because it is not equal to [piercing] the lurking-places of the will, let us not on that account make light of crimes of the will in God's sight…. Nothing from whence any sin whatsoever proceeds is remote from His sight; because He is neither ignorant, nor does He omit to decree it to judgment."[xxxvi]

Tertullian challenged the argument of some who, while acknowledging that God created the soul, deny that we need to fear God’s judgment for sin. "There are some who, though they do not deny the existence of God, hold withal that He is neither Searcher, nor Ruler, nor Judge; treating with special disdain those of us who go over to Christ out of fear of a coming judgment … not even regarding Him as capable of anger…. But these very persons elsewhere, confessing that the soul is divine, and bestowed on us by God, stumble against a testimony of the soul itself. . . . For if either divine or God-given, it doubtless knows its giver; and if it knows Him, it undoubtedly fears Him too. . . . Whence, then, the soul's natural fear of God, if God cannot be angry? How is there any dread of Him whom nothing offends?"[xxxvii]

Origen (185–253 AD)

Origen, the prolific early Christian theologian, viewed natural law as an inner rational moral faculty implanted by God, guiding the soul toward truth and convicting it of sin. "It is naturally innate within men, both Jews and Gentiles."[xxxviii]

The unity of creation points to a single Creator. "[C]onvinced by what we see, in the admirable order of the world, we should worship the Maker of it as the one Author of one effect, and which, as being wholly in harmony with itself, cannot on that account have been the work of many makers."[xxxix] People can understand the Creator, in part, because we have a mind in harmony with God’s Mind. "The mind bears a certain relationship to God, of whom the mind itself is an intellectual image, and that by means of this it may come to some knowledge of the nature of divinity."[xl]

Origen likened natural law to a teacher that educates the soul in moral discernment, revealing right and wrong through the conscience, and exposing human inadequacy: "The conscience functions like a pedagogue to the soul, a guide and companion, as it were, so that it might admonish it concerning better things or correct and convict it of faults."[xli]

Natural law reveals human moral accountability. "It is not surprising that the same God has sown in the minds of all men the seeds of the same truths which he taught through the prophets and the Savior, so that at the divine judgment every man may be without excuse, having the law written in his heart."[xlii]

Natural law is substantially the same as the moral law in Scripture. People can perceive by nature “that they should not commit murder or adultery, they ought not to steal, they should not speak falsely, they should honor father and mother, and the like."[xliii]  “[W]hat could be nearer to the natural moral senses than that those things men do not want done to themselves, they should not do to others?"[xliv]

Natural law is a universal direction to virtue that condemns all people. "One finds that God has in fact given to man every disposition and every drive by which he can press forward and advance toward virtue…. One finds then that God has supplied these things universally to all men.”[xlv] "The Gentile … stands condemned by his conscience before the natural moral law."[xlvi]

Eusebius of Caesarea (260–339 AD)

Eusebius of Caesarea, in his monumental Preparation for the Gospel, systematically argued that the Logos is a providential guide for the Gentiles.

The Logos is "the eternal Word of the everlasting God . . . the most strong and firm support of the universe."[xlvii] The Logos provides a lawlike structure for creation: "by God's logos and law first of all the firmament of heaven is firmly fixed."[xlviii] 

Eusebius saw an alignment between the monotheism of Plato and Moses, preparing the world for the Gospel's proclamation of one true God, as natural law requires unity in creation. "As Moses declares, 'Hear, O Israel, the LORD our God is one LORD' [Deut. 6:4], so Plato in Timaeus: 'Have we then been right in speaking of one heaven, or was it more correct to say that there are many and infinite? One, if indeed it is to have been created according to the pattern.' For the divine oracles teach that there is one God, the Father and Creator of the universe, and Plato agrees, affirming the unity of the divine architect."[xlix]

Eusebius documented how natural philosophy grasped the difference between the eternal divine being and the transient creation, preparing for Moses’ revelation about the eternal unchanging God. "[Plato in Timaeus]: What is that which always is and has no becoming? And what is that which is becoming and never is? The former is that which may be comprehended by intelligence combined with reason, being always in the same conditions; but that which is created is created by nature, and is passing in and out of a state of becoming. . . . Does it not plainly appear that the admirable philosopher has altered the oracle which in Moses declared 'I AM THAT I AM' into 'What is that which always is and has no becoming?'"[l]

God's benevolence, seen through natural philosophy, fosters a moral intuition of Divine generosity that prepares souls for the Gospel's message of unmerited mercy. "He [the Creator] was good. And in one who is good no jealousy of anything ever finds place. . . . The Hebrew Scriptures teach that the Good itself is nothing else than God, and Plato concurs, declaring the supreme God as the source of all goodness, free from envy."[li]

The Greeks’ failure to fully uphold divine righteousness, amid idolatrous and inconsistent doctrines, underscored the need for redemption. "But now, by God's grace we may say, through our Savior’s teaching in the Gospel all nations from all parts of the earth have been delivered from the bondage of the demons, and sing the praise of that God whom we have learned to be the only Savior, and King, and God of the whole world."[lii]

Augustine of Hippo (354–430 AD)

Augustine taught that natural law is foundational to the doctrine of grace. It is the inborn moral guide written on the heart that reveals sin’s reality and requires Christ’s redemption.

By showing the Creator’s existence and humanity’s moral defects, natural law prepares the soul for the Gospel’s renewal of the divine image. “The image of God in man, though marred by sin, retains the law of nature in the rational soul, which seeks the good and knows its Creator.”[liii]

Natural law amplifies sin’s visibility, compounding original sin with personal failings. “Sin could not be taken away even by the law, which entered that sin might the more abound, whether it be the law of nature, under which every man when arrived at years of discretion only proceeds to add his own sins to original sin.”[liv]

Natural law has an indelible presence in human conscience, persisting despite sin’s corruption. “Theft is punished by Thy law, O Lord, and by the law written in men's hearts, which iniquity itself cannot blot out.”[lv]

Natural law is a universal inclination toward peace, convicting humanity of our failure to achieve permanent tranquility. “Of the universal peace which the law of nature preserves through all disturbances, and by which everyone reaches his desert in a way regulated by the just judge.”[lvi]

While natural law reveals moral truth, it cannot save. “Neither the knowledge of God's law, nor nature, nor the mere remission of sins is that grace which is given to us through our Lord Jesus Christ; but it is this very grace which accomplishes the fulfilment of the law, and the liberation of nature, and the removal of the dominion of sin.”[lvii]

Conclusion

Building on the insights of the early Church Fathers, Lutherans can explain why the universal natural law prepares the world for the Gospel. Humanity is morally accountable to God, and urgently needs forgiveness, which only the Gospel can provide.

[i] First Apology, Chapter 20.

[ii] Second Apology, Chapter 10.

[iii] Ibid.

[iv] First Apology, Chapter 18.

[v] Ibid., Chapter 59.

[vi] Ibid., Chapter 28.

[vii] On the Resurrection, Chapter 8.

[viii] First Apology, Chapter 20.

[ix] Ibid., Chapter 18.

[x] Ibid., Chapter 12.

[xi] Second Apology, Chapter 13.

[xii] Against Heresies, Book IV, Chapter 13, Section 3.

[xiii] Ibid., Chapter 15, Section 1.

[xiv] Ibid., Book II, Chapter 6, Section 1.

[xv] Ibid., Book III, Chapter 25, Section 1.

[xvi] Ibid., Book IV, Chapter 6, Section 6.

[xvii] Ibid., Book III, Chapter 5, Section 5.

[xviii] Ibid., Book V, Chapter 23, Section 1.

[xix] Ibid., Book V, Chapter 27, Section 2.

[xx] Stromata, Book I, Chapter 5.

[xxi] Ibid., Chapter 11.

[xxii] Ibid., Chapter 13.

[xxiii] Exhortation to the Heathen, Chapter 6.

[xxiv] Stromata, Book I, Chapter 28.

[xxv] The Paedagogus, Book 2, Chapter 10.

[xxvi] Ibid.

[xxvii] Ibid., Book I, Chapter 13.

[xxviii] Ibid.

[xxix] Stromata, Book II, Chapter 6.

[xxx] Exhortation to the Heathen, Chapter 10.

[xxxi] An Answer to the Jews, Chapter 2.

[xxxii] Ibid.

[xxxiii] Testimony of the Soul, Chapter 6.

[xxxiv] Apology, Chapter 17.

[xxxv] On Repentance, Chapter 6.

[xxxvi] Ibid., Chapter 3.

[xxxvii] The Soul’s Testimony, Chapter 2.

[xxxviii] Commentary on Romans, Book III, Chapter 6.

[xxxix] Contra Celsum 1.23.

[xl] De Principiis 1.1.7.

[xli] Commentary on Romans, Book II, Chapter 9.

[xlii] Against Celsus, Book I, Chapter 4.

[xliii] Commentary on Romans, Book II, Chapter 9.

[xliv] Ibid.

[xlv] Ibid., Book III, Chapter 6.

[xlvi] Ibid., Book III, Chapter 2.

[xlvii] Preparation for the Gospel, Book 7, Chapter 13.

[xlviii] Ibid., Book 7, Chapter 10.

[xlix] Ibid., Book 11, Chapter 13.

[l] Ibid., Book 11, Chapter 9.

[li] Ibid., Book 11, Chapter 21.

[lii] Ibid., Book 7, Chapter 16.

[liii] On the Trinity, Book 14, Chapter 15.

[liv] On Merit and the Forgiveness of Sins, Book I, Chapter 12.

[lv] Confessions, Book 2, Chapter 4.

[lvi] City of God, Book 19, Chapter 13.

[lvii] On Grace and Free Will, Chapter 12.

Britton Weimer (JD, University of Minnesota Law School) is a confessional Lutheran (WELS) and a commercial attorney. He is the co-author of Britton Weimer and Paul Johnson, Searching for Answers: The Unquenchable Thirst (AMG Publishers 2002).