Reformed Theology is the systematic theology formulated by thinkers in the Reformed tradition during and after the Protestant Reformation of the sixteenth century. It is a continuation of the catholic (universal) and orthodox (biblically sound) theology that the church has confessed since its earliest days. It was officially endorsed by the Reformed synods and assemblies of the seventeenth century. God’s covenant is an overarching concept in Reformed theology. In fact, it has been rightly noted that Reformed theology is simply covenant theology. The redemption of the elect is rooted in the covenant of peace or redemption (i.e., the pactum salutis). The Reformed doctrine of the covenant of works (or life) informs the relationship between the law and the gospel as it relates to justification. The covenant of grace is the means by which God saves sinners through faith in His Son Jesus Christ. Reformed theology structures its understanding of worship, the sacraments, the church, and eschatology in light of the covenant of grace. It teaches that God rather than man is sovereign in the salvation of sinners, and it seeks to present the biblical teaching about God, man, sin, Christ, and salvation in one coherent system of doctrine.
In the centuries leading up to the Reformation, John Wycliffe (1320–84) and Jan Hus (1371–1415) protested the teachings and practices of the Roman Catholic Church. Wycliffe was “the morning star of the Reformation,” translating the Scriptures from Latin into the English vernacular. Hus adopted Wycliffe’s commitment to Scripture. He rejected the claim that the visible church holds the infallible interpretation of Scripture and adhered to what the Reformation would call the principle of sola Scriptura. Together, the labors of these two pre-Reformers influenced those who would spearhead the Reformation throughout Europe in the sixteenth century.
On October 31, 1517, Martin Luther set the Protestant Reformation in motion in Germany—nailing his Ninety-Five Theses to the church door in Wittenberg. Burdened under the spiritual bondage of the medieval penitential system, Luther sought answers to questions regarding assurance of salvation. While lecturing through the Apostle Paul’s letter to the Romans, Luther embraced the doctrine of justification by faith alone. After accepting the biblical principle of sola Scriptura, Luther began promulgating the biblical teaching that salvation is by God’s grace alone (sola gratia through faith alone (sola fidei) in Christ alone (solus Christus) to the glory of God alone (soli Deo gloria).
While the Reformation advanced in Germany, ecclesiastical reform began to spread throughout Europe. Huldrych Zwingli and John Calvin led a Reformation movement in Switzerland, and John Knox did the same in Scotland. Although theological nuances and differences existed between these Reformers on several points of doctrine, they are key figures in Reformed theology and uniformly adhered to the five solas of the Reformation and the five points of Calvinism (i.e., the doctrines of grace).
The Reformers’ expositional preaching of Scripture and systematic theological writings—such as Calvin’s Institutes of the Christian Religion—laid the theological groundwork for the post-Reformation confessions and catechisms produced by Reformed synods and assemblies. Among the most influential Reformed confessions and catechisms are the Three Forms of Unity and the Westminster Standards. These documents are the product of the faithful labors of seventeenth-century Protestant theologians.
The doctrines of grace were framed at the Synod of Dort under the title “The Five Main Points of Doctrine in Dispute in the Netherlands.” They were formulated in response to the five points of semi-Pelagianism taught by the Remonstrants, who were disciples of Jacobus Arminius, a professor of theology at the University of Leiden._ _The five main points of doctrine formulated at Dort highlighted the biblical teaching on total depravity, unconditional election, limited (particular or definite) atonement, irresistible grace, and the perseverance of the saints. At the beginning of the twentieth century, these five doctrines began to be popularly taught under the acronym TULIP. The doctrines of grace are interrelated in such a way that they form a logically coherent system of salvation.
The distance between God and the creature is so great, that although reasonable creatures do owe obedience unto him as their Creator, yet they could never have any fruition of him as their blessedness and reward, but by some voluntary condescension on God's part, which he hath been pleased to express by way of covenant.
In Reformed theology we constantly test our doctrine by going back to our fundamental understanding of the character of God. And I really think that’s the central unique factor of Reformed theology; it is that it is relentlessly committed to maintain the purity of the doctrine of God through every other element of our theology.
“Catholic, Evangelical, and Reformed”, What Is Reformed Theology?
The formal cause of the Reformation was Sola Scriptura, meaning that the only source of special written revelation that has the authority to bind the conscience absolutely is the Bible. The material cause was declared by the formula sola fide, meaning that justification is by faith alone.
God the great Creator of all things doth uphold, direct, dispose, and govern all creatures, actions, and things, from the greatest even to the least, by his most wise and holy providence, according to his infallible foreknowledge, and the free and immutable counsel of his own will, to the praise of the glory of his wisdom, power, justice, goodness, and mercy.
It is precisely the same system of truth which is embodied in all the great historic Reformed confessions; it matters not whether the document emanates from Zurich or Bern or Basel or Geneva, whether it sums up the Swiss development as in the second Helvetic Confession, or publishes the faith of the National Reformed Churches of France, or Scotland, or Holland, or the Palatinate, or Hungary, Poland, Bohemia, or England; or republishes the established Reformed doctrine in opposition to new contradictions, as in the Canons of Dort (in which the entire Reformed world concurred), or the Westminster Confession (to which the whole of Puritan Britain gave its assent), or the Swiss Form of Consent (which represents the mature judgment of Switzerland upon the recently proposed novelties of doctrine).
The Works of Benjamin B. Warfield, vol. 5, Calvin and Calvinism, 361–62