In the Summer of 1570 the Reformed Reformation in Heidelberg faced a crisis. Several of the Zwinglians, who had sided with Erastus against the Calvinist order in the Palatinate, were perceived by their Calvinist opponents to be arguing for something that looked like Arianism. This was a crisis because the Lutheran electors were already suspicious of Frederick III (1515–76) because of his Calvinism. As such, he denied the Lutheran version of the communication of properties (communicatio idiomatum), the ubiquity of Christ’s humanity, and the Lutheran view of the Supper. The Lutherans had already summoned him to the Colloquy of Maulbronn in 1564 to answer for his Reformed convictions and, had he failed to satisfy them, he faced a possible invasion. Thus, both the political and the theological stakes were high in the discovery of any heresy against the ecumenical faith in Heidelberg.
One of the heretics, Adam Neuser (c. 1530–76) escaped arrest and fled to Turkey but the controversy with the anti-Trinitiarians continued until December 23, 1572 when, despite the judgment of the civil judges that he should receive only corporal and not capital punishment, the Elector bowed to pressure from the theologians, including Caspar Olevianus (1536–87), and ordered that capital punished be applied to Johann Sylvan.
That heresy against the ecumenical faith should be a capital crime was hardly unusual in pre-Modern Christendom nor was it unusual to see theologians demanding the state to enforce religious orthodoxy. This episode, however, illustrates the intensity with which the Heidelberg Calvinists held to the ancient, ecumenical Trinitarian faith, including the doctrine of the eternal generation of the Son. When Kevin Giles subtitles his defense of eternal generation, “maintaining orthodoxy in Trinitarian theology,” he echoes that tradition. The Heidelberg Calvinists held to the ancient, ecumenical Trinitarian faith, including the doctrine of the eternal generation of the Son. Click To Tweet
Caspar Olevianus is typically understood only as figure relative to the development of Reformed covenant theology or in light of his contribution to the Heidelberg Catechism (1563). That is a truncated view of the nature of Reformed covenant theology and of Olevianus’ contribution to it. For Olevianus, catholic orthodoxy, including the eternal generation of the Son, was an element of the substance of the covenant of grace.
Peter the Lombard (c. 1100–60) wrote the most influential theological textbook in the Medieval period. Lecturing on his Sentences (c. 1158) was a necessary step in becoming an accredited theologian in the university. His appropriation and synthesis of the Christian tradition influenced Western theology for 400 years after it first appeared. Though we are not always aware of it, Christians continue to rely on Peter’s formulations. So it is instructive to note that for him to teach the doctrine of God (book 1) was to teach the doctrine of the Trinity and for him to teach doctrine of the Trinity was to teach the doctrine of the eternal generation of the Son.
As he understood the history of Christian teaching, the doctrine of eternal generation was a basic part of Christian orthodoxy. Beginning in dist. 4 he treated as axiomatic for Christians to say “[w]e know, and it is true beyond doubt, that God the Father begot the Son…”. He quoted the Nicene-Constantinopolitan Creed, “Light of light, true God of true God,” which he took to be the ecumenical confession of the eternal generation of the Son. He carried on this discussion through dist. 5, citing along the way Augustine, On the Trinity, Fulgentius of Ruspe, On Faith, Hilary, On the Trinity, Ambrose, On Faith, as well as Chrysostom, and Origen.
Thus, when John Calvin (1509–64) explained the doctrine of the Trinity, in Institutes 1.13, he spoke first to the unity and simplicity of God (1.13.1), then to the subsistence of the Father, Son, and Holy Spirit (1.13.2–6). His third topic under heading of the Trinity was the deity of the Son and the Spirit (1.13.7). It would be “absurd” to imagine that the “Word of God” (verbum Dei) refers to anything temporary. Rather, that verbum is the eternal wisdom of God that resides with God. Thus it was the Spirit of Christ who spoke through the Old Testament prophets (1 Pet 1:1). “Because Christ was not yet manifested [under the Old Testament], it is necessary to understand that the Word was begotten of the Father before from eternity.” Later, in the Institutes, he re-asserted the doctrine of the eternal generation (ab aeterna genitura) of the Son against Michael Servetus (c. 1509/11–53) and Nestorius’ error of making Christ a composition of human and divine elements.
In his lectures on Heidelberg Catechism 25, Olevianus’ colleague, Zacharias Ursinus (1534–83), taught explicitly the doctrine of the eternal generation of the Son.
Therefore the order of the existing of the persons is this: the Father is the first person and the source of divinity of the Son and of the Spirit. Because to him deity is communicated by no one but from himself he communicates deity to the Son and to the Holy Spirit. The Son is the second person [of the Trinity] because deity is communicated to him from the Father through eternal generation….
Ursinus would appeal to the datum of the Son’s eternal generation throughout his lectures, e.g., in his defense of the deity of the Son under Heidelberg Catechism 33. In response to those who, by confusing the creature with the Creator, denied the Son’s eternal deity. The objection says: “Whatever has a beginning is not eternal. The Son has a beginning. Therefore he is not that eternal Jehovah, who is the Father.”
Ursinus responded, “He is not eternal who has a beginning of essence and of time. But the Son is not said to have a beginning of essence and of time but only of person and order. For he has one and eternal essence with the Father, not of time, but by eternal generation.” One finds the same sorts of arguments in early Reformed orthodox theologians such as Thomas Cartwright (1535–1603), Franciscus Junius (1545–1602), and William Perkins (1558–1602).
The covenantal connection
Reformed covenant theology inherited its most basic structures from the Patristic reaction to the Gnostics and the Marcionites. Barnabas (c. AD 120), Justin (c. AD 150), and Irenaeus (c. AD 170) all made substantially identical arguments in favor of the unity of salvation between the Old and New Testaments. By 1524 Huldrych Zwingli (1484–1531) was employing similar and even more explicit arguments in favor of the unity of the covenant of grace against the Anabaptists, in whom he discerned a similar atomizing tendency. His successor as Antistes in Zürich, Heinrich Bullinger (1504–75), in his 1534 treatise, On the Testament or Covenant of God elaborated on Zwingli’s arguments for the unity of the covenant of grace against the Anabaptists. In the work of Ursinus and Olevianus, however, Reformed covenant theology reached a turning point. Arguably, Ursinus was the first to use explicitly the language of the covenant of nature (foedus naturale), in his 1562 Summa theologiae (Q. 36). The covenant of nature would shortly come to be known as the covenant of works.
As Ursinus mainly worked out his covenant theology in the context of his lectures on the Heidelberg Catechism, Olevianus developed his covenant theology mainly in the context of his three commentaries on the Apostles’ Creed, Firm Foundation (1567), the Exposition of the Apostles’ Creed (1576), and On the Substance of the Covenant of Grace Between God and the Elect (1585).
Olevianus was born in the ancient imperial city of Trier, which distinction he shares with Ambrose and Karl Marx. The Reformation had not made many inroads into Trier by 1536 so he was catechized in Romanism but received a good Latin education before going off to university in Paris and Orléans, the latter a hotbed of Protestant sympathies, where he joined the underground Reformed “churches under the cross.” He took his Juris Doctor at the Université de Bourges in 1557 and returned home to practice law but left Trier after 8 months to pursue theological studies in Geneva and later Zürich. In the former he studied with Calvin and Theodore Beza (1519–1605). In the latter he studied with Peter Martyr Vermigli (1499–1562) and Bullinger. From Zürich he returned to Geneva where Guillaume Farel (1489–1565) urged him, as he had earlier urged Calvin, to cut short his studies and pursue the Reformation of Trier. That he did unsuccessfully but his efforts did not go unnoticed (nor had his friendship with Frederick III’s second son Herman gone unnoticed) and when his attempt to bring the Reformed reformation to Trier landed him in jail, Frederick III bailed him out and gave him a position in Heidelberg.
Eternal generation is part of our Firm Foundation
His first major exposition of covenant theology was in the form of an expanded catechism published, in German, as Vester Grund (Firm Foundation) in 1567. In this work, aimed at the laity, he wrote “[Christians] forget that it is easy, not difficult, to find a firm foundation if they just take hold of the articles of our old, true, undoubted Christian faith.” Published in the wake of the final edition of the Heidelberg Catechism, Firm Foundation echoes the catechism and serves as a commentary on large sections of it. The articles to which he referred were, those things necessary for a Christian to believe, i.e., “All that is promised us in the Gospel, which the articles of our catholic, undoubted Christian faith teach us in sum.” Note that, in the Heidelberg Catechism, the articles of the Apostles’ Creed are gospel, not law, and form the middle of the catechism, which organized in three parts: law (1–11), gospel (12–85), and sanctification (86–129).
He followed the ancient Christian tradition of turning to the eternal generation of the Son in his exposition of the doctrine of the Trinity. In Q. 21 of Firm Foundation he appealed to the traditional proof texts in defense of the traditional formula, one divine being in three distinct persons, which he linked to Christian baptism. In Q. 22, as proof of the deity of the Son, he affirmed the “Son is true, essential God precisely because He is the Son of God, who from eternity was generated from the divine essence of the Father (John 1[:2], Rom. 9[:5], Heb. 1[:3]). John 17[:5]: ‘Father, glorify me with the glory which I had with you before the foundation of the world.’ See also Romans 1 and Jeremiah 33.” Under his exposition of the first article of the Creed, “I believe in God the Father…” (Q. 27), he explained that we call God Father for two reasons, first “in view of His Son Christ, who is the eternal, essential wisdom of the Father, who was begotten of Him from eternity (Prov. 8[:23]), and who after taking upon Himself a human nature, was revealed as the Son of God (Rom. 1[:4]; Luke 1[:35]).”
After explaining the threefold office of Christ for us (Prophet, Priest, and King), he turned to his anointing as Messiah and the distinction between our adoption as son and Christ’s relation to the Father:
63 Q. Since then we are all children of God, why does Scripture call Christ His only begotten Son?
1. So that a distinction is made between Christ and all believers. For Christ is and is called the only begotten Son of God because He alone is the eternal and natural Son of the Father, begotten from eternity of the substance of the Father and therefore true God, in whom we should believe. We, however, are called and actually are children of God not by nature but by grace: God has adopted us as His children by incorporating us into His Son through faith and the working of the Holy Spirit and by making us now His true and living members—we who otherwise were by nature children of wrath (Eph. 2[:3]).
Christian certainty about salvation and adoption into God’s grace is grounded in the Son’s natural, eternal, generation. He repeated this same point in this 1576 Exposition of the Apostles’ Creed.
Eternal generation is of the substance of the covenant of grace
Perhaps Olevianus’ most interesting use of the doctrine of eternal generation, however, occurred in his most extended exploration of covenant theology, in On the Substance of the Covenant of Grace Between God and the Elect (1585). The work is in two parts: 1) the substance of the covenant of grace, structured by the 12 articles of the Apostles’ Creed, and 2) the external administration of the substance of the covenant of grace in the visible church.
He began with a brief exposition of Jeremiah 31:31–33, which, with Barnabas, Justin, Irenaeus, and the first-generation Reformers, he understood as a contrast between Moses and Christ. The New Covenant is a promise of the gospel, the substance of the covenant of grace. Each of the articles of the faith are to be explained relative to the covenant of grace. God is the author of the covenant of grace. Man is considered as the recipient of the covenant of grace.
Even under the New Covenant, however, not all who participate in the external administration receive the substance, which has to be outwardly administered in the visible church. Only the elect, however, receive the substance of the covenant, “for to all the elect and to them alone, this part, the remission of sins, renewal in the image of God, and the knowledge of God itself is promised.”
As noted, however, the substance of the covenant must be administered. The promise of the covenant of grace, in Genesis 17, says, “this is my covenant in your flesh. Certainly the substance of that covenant was not in their flesh.” After all, not all the hearts of the Israelites and their children were circumcised, which is the substance of the promise of the covenant of grace, which is offered freely in the external administration of the covenant. Almost unexpectedly Olevianus pivoted back to the substance of the covenant of grace, in which he quite pointed included the doctrine of the eternal generation of the Son:
Therefore, the covenant of grace, if you see its essence, is a promise and oath unto God, a gift by God, never to be angry with us (Isa 54) and our adoption unto sons of God, and heirs of eternal life in Jesus Christ, the eternal and only begotten Son of God, the seed of Abraham who is Christ. And [it is a promise and oath] to all men, who, by faith, who are given freely to be engrafted to this seed, and in whom they are freely justified and glorified without condition or any stipulation of knowledge bonae ex ipsorum: in order that his gracious goodness might be celebrated by us in this life and life eternal (Hos 2; Isa 54; Gen 22; Heb chapters 1, 6; Gal 3:15–18, 22, 26, 29).
One of the grounds of the reliability of the covenant of grace was Olevianus’ Trinitarian doctrine of God: “The God who promises is Father, Son and Holy Spirit setting up that covenant of adoption in the person of the Mediator or the Logos incarnate…”. In other words, the substance of the covenant of grace rests in the nature of God and particularly in the nature of God the Son, the Mediator of the covenant. He qualified the Son as the “eternal and only begotten Son.” By grace alone, believers are adopted sons of God, in the eternally generated Son of God. In the next section he made that connection explicit, again focusing on the eternal generation of the Son.
God is a spiritual essence, eternal, infinite, omnipresent, intelligent, true, good, pure, omnipotent, most free, just, merciful. The eternal Father, who begat from eternity, from his substance, the Son, his representation of his being. And the Son was begotten from the Father from eternity. And the Holy Spirit proceeds from eternity from the Father and the Son.
The Son is a reliable Mediator and Redeemer and worthy himself to be the substance of the covenant given to all the elect because he is consubstantial, from eternity, with the Father. In Christ, the Father elects, in the Holy Spirit he applies the work of Christ to the elect in the external administration of the covenant of grace. The Son is a reliable Mediator and Redeemer and worthy himself to be the substance of the covenant given to all the elect because he is consubstantial, from eternity, with the Father. Click To Tweet
In his discussion of the nature and need of humanity after the fall he contrasted the natural state of the Son with the corruption of human nature in the fall. He for whom it was not robbery to be considered equal to God “for he was from eternity begotten of the substance of the Father, and there also equal in all things, which we confess according to the writing of the Athanasian Creed,” nevertheless poured himself out for us.
One of the contributions that Olevianus made to Reformed covenant theology, which is not always been appreciated, was his development of what would come to be known as the “covenant of redemption” (pactum salutis), i.e., the pre-temporal covenant between the Father and the Son, which David VanDrunen and I have called “The Covenant Before the Covenants.” In De substantia 1.2 he turned to that pre-temporal covenant as another ground of the Christian’s confidence and the eternal generation of the Son again appeared as element of the substance of the covenant of grace.
In the covenant of redemption there is a solemn promise (sponsio) that the Son would be our surety (fideiussio) and to fulfill it the Mediator had to be the “only begotten Son of God” constituted as our head and eternal Lord, in our flesh. On account of our adoption, because of the Father’s infinite love for us, had also to be begotten from eternity.The number and influence of contemporary evangelical theologians who have rejected the doctrine of the eternal generation of the Son is impressive. For Caspar Olevianus, however, the doctrine was ... a biblical and ecumenical truth Click To Tweet
He hit this same note again under the third article of the Creed, “conceived by the Holy Spirit, born of the Virgin Mary.” In order that the gracious covenant of our adoption might be “most firm” God the Son, “begotten of the Father from eternity” had to become incarnate, in the womb of the Virgin, by the work of the Spirit.
If Kevin Giles is correct, American evangelical and Reformed theologians since Charles Hodge (1797–1878) have doubted or rejected the doctrine of the eternal generation of the Son. The number and influence of contemporary evangelical theologians who have rejected the doctrine of the eternal generation of the Son is impressive.
For Caspar Olevianus, however, the doctrine was neither disposable nor the product of a nebulous “Greek philosophy” but a biblical and ecumenical truth confessed in the Athanasian Creed, which he recited early in De substantia to drive home the catholicity of the doctrine. It was also therefore, of the essence of the covenant of grace because it grounds the redemption of the elect and their inclusion in the covenant of grace in the very nature of God the Son and in his eternal consubstantiality with the Father and with us in his incarnation.
 For a brief discussion of the controversy and a survey of some of the literature see R. Scott Clark, Caspar Olevian and the Substance of the Covenant, Reformed Historical-Theological Studies (Grand Rapids: Reformation Heritage Books, 2008), 75–77. See also Benjamin R. Merkle, Defending the Trinity in the Reformed Palatinate (Oxford: Oxford University Press, 2015).
 Kevin Giles, The Eternal Generation of the Son: Maintaining Orthodoxy in Trinitarian Theology (Downers Grove: IVP Academic, 2012).
 Peter Lombard, The Sentences, ed. Joseph Goering, Giulio Silano, trans. Giulio Silano et al. 4 vol. Mediaeval Sources in Translation (Toronto: Pontifical Institute of Mediaeval Studies, 2007–10), 1.4.1.
 On the history of the doctrine of the eternal generation of the Son see Giles, The Eternal Generation of the Son.
 Johannes Calvinus, Institutio christianae religionis 1.13.7 in Joannis Calvini, Opera Selecta, ed. P. Barth and G. Niesel, 5. vol. (Munich: Christian Kaiser, 1962), 3.117.1. Hereafter, OS. On the development of the doctrine of eternal generation within Reformed theology from Calvin through the period of High Reformed orthodoxy see Brannon Ellis, Calvin, Classical Trinitarianism, and the Aseity of the Son (Oxford: Oxford University Press, 2012).
 OS 3.117.5.
 OS, 3.117.8–9.
 “…necesse est Sermonem
intelligere ante secula ex Patre genitum” (OS, 3.117.10–11).
 Institutes, 2.14.5; OS. 3.465.14. There is debate in the secondary literature about how to understand Calvin’s doctrine of eternal generation. See e.g., Benjamin B. Warfield, The Works of Benjamin B. Warfield: Calvin and Calvinism, vol. 5 (New York: Oxford University Press, 1932), 245–51; Ellis, Calvin, Classical Trinitarianism, 39–63, 169–73.
 “Ordo itaque personarum in existendo hic est. Pater est prima persona, et quasi fons divinitatis filii et Spiritus sancti: quia deitas ei a nullo est communicta, sed ipse deitatem communicat filio et Spiritui sancto. Filius secunda persona: quia deitas ei a patre communicatur per aeternam generationem.” Zacharias Ursinus, Corpus Doctrinae Ecclesiarum a Papatu Romano Reformatarum (Hanover: 1634), 130.
 “2. Habens principium non est aeternus. Filius habet principium. Ergo non est aeternus ille Iehoua, qui est pater. Respond. ad maiorem. Aeternus non est, habens principium essentiae et temporis. Filius autem dicitur habere principium non essentiae et temporis, sed solummodo personae, et ordinis. Habet enim unam et aeternall essentiam cum patre, non temporali, sed aeterna genratione. ” Corpus doctrinae, 200.
 Thomas Cartwright, Christian Religion (London, 1611), 11, 12, 137,
 Franciscus Junius, Defensio Catholicae Doctrinae De S. Trinitate Personarum in Unitate Essentiae Dei, Adversus Samosatenicos Errores (Geneva, 1590), 11, 13, 15, 17.
 E.g., William Perkins, A Golden Chain in The Works of Williams Perkins, 10 vol. ed. Joel Beeke and Derek W. H. Thomas (Grand Rapids: Reformation Heritage Books), 6.21, 48.
 Heinrich Bullinger, De testamento seu foedere dei unico et aeterno brevis expositio (Zürich, 1534), translated as A Brief Exposition of the One and Eternal Testament or Covenant of God (1534) in C. S. McCoy and J. W. Baker, Fountainhead of Federalism (Louisville: WJKP, 1991), 99–138.
 Zacharias Ursinus, Summa theologiae in D. zachariae ursini…opera theologica, ed. Q. Reuter, 3 vol., (Heidelberg, 1612), 1.14. For more on the history of covenant theology see R. Scott Clark, “Christ and Covenant: Federal Theology in Orthodoxy,” In Companion to Reformed Orthodoxy, ed. Herman Selderhuis (Leiden: Brill, 2013), 403–28.
 Vester Grund (Heidelberg, 1567) is translated as Caspar Olevianus, A Firm Foundation. An Aid to Interpreting the Heidelberg Catechism, trans, Lyle D. Bierma (Grand Rapids: Baker Books, 1995). Expositio symboli apostolici (Frankfurt, 1576) is translated as Caspar Olevianus, An Exposition of the Apostles’ Creed, trans. Lyle D. Bierma, Classic Reformed Theology, ed. R. Scott Clark (Grand Rapids: Reformation Heritage Books, 2009). Caspar Olevianus, De substantia foederis inter deum et electos (Geneva, 1585) is expected to appear in the Classic Reformed Theology series.
 This brief sketch is drawn from the “Biographical and Historical Introduction” to Caspar Olevianus. An Exposition of the Apostles’ Creed, i—xxx.
 Olevianus, Firm Foundation, xli.
 Philip Schaff, The Creeds of Christendom, with a History and Critical Notes: The Evangelical Protestant Creeds, with Translations, vol. 3 (New York: Harper & Brothers, 1882), 314.
 Olevianus, Firm Foundation, 18.
 Olevianus, Firm Foundation, 21.
 Olevianus, Firm Foundation, 46. Emphasis original signalling allusions to the Heidelberg Catechism.
 Olevianus, Exposition, 62.
 Olevianus, De substantia, 1.1.1 and 1.1.2.
 Olevianus, De substantia, 1.1.3.
 Olevianus, De substantia, 1.1.3.
 Olevianus, De substantia, 1.1.2.
 “Nam iis omnibus et solis utraque illa pars promittitur, peccatorum remissio et instauratio ad Dei imaginem” (De substantia, 1.1.2).
 Olevianus, De substantia, 1.1.2.
 “Foedus itaque gratuitum, si essentiam eius spectes, est promissa et iurata à Deo donatio suimet in Deum nunquam nobis irascentem Isai. 54. et assumtio nostri in filios Dei et haeredes vitae aeternae in Iesu Christo aeterno et unigenito Dei Filio,facta semini Abrahae qui est Christus, et omnibus qui fide gratis donati huic semini inseruntur, et in eo gratis iustificantur et glorificantur citra conditionem aut stipulationem ullius cogitationis bonae ex ipsorum viribus: ut pro gratuita sua bonitate ab iis celebretur in hac et aeterna vita, Hos. 2. Isai. 54. Genes. 22. Heb. 1. & 6. Gal. 3. v. 15. 16. 17. 18. 22. 26. 29” (De substantia, 1.1.2).
 “Deus promittens est Pater, Filius, et Spiritus Sanctus erigens foedus hoc adoptionis in persona Mediatoris seu λόγῳ incarnato…” (De substantia, 1.1.3).
 “Deus est essentia spiritualis, aeterna, infinita, omnipraesens, intelligens, verax, bona, pura, omnipotens, liberrima, iusta, misericors: Pater aeternus, qui Filium characterem suae hypostaseos ab aeterno genuit è sua substantia: et Filius ab aeterno à Patre genitus: et Spiritus sanctus ab aeterno procedens à Patre et Filio….” (De substantia, 1.1.4).
 “…erat enim ab aeterno è substantia Patris genitus, eoque et aequalis in omnibus, ut antea secundum scripturas ex symbolo Athanasii confessi sumus” (De substantia, 1.1.8).
 “The Covenant Before the Covenants,”in R. Scott Clark, ed. Covenant, Justification and Pastoral Ministry: Essays by the Faculty of Westminster Seminary California (Phillipsburg: P&R Publishing, 2006), 167–96.
 Olevianus, De substantia, 1.2.4.
 Olevianus, De substantia, 1.3.1.
 Giles, The Eternal Generation, 30–31.
 Giles, ibid. 30–37.