Heidelberg Catechism

The Heidelberg Catechism (1563), one of the Three Forms of Unity, is a Reformed catechism taking the form of a series of questions and answers, for use in teaching Reformed Christian doctrine. It was published in 1563 in Heidelberg, Germany. Its original title translates to Catechism, or Christian Instruction, according to the Usages of the Churches and Schools of the Electoral Palatinate. Commissioned by the prince-elector of the Electoral Palatinate, it is sometimes referred to as the 'Palatinate Catechism.' It has been translated into many languages and is regarded as one of the most influential of the Reformed catechisms. Today, the Catechism is "probably the most frequently read Reformed confessional text worldwide".

Frederick III, sovereign of the Electoral Palatinate from 1559 to 1576, was the first German prince who professed Reformed doctrine although he was officially Lutheran. The Peace of Augsburg of 1555 originally granted toleration only for Lutherans under Lutheran princes (due to the principle of cuius regio, eius religio). Frederick wanted to even out the religious situation of his highly Lutheran realm within the primarily Roman Catholic Holy Roman Empire. He commissioned the composition of a new catechism for his realm, which would serve to both teach the young and settle the differences in doctrine between Lutherans and the Reformed. One of the aims of the catechism was to counteract the teachings of the Roman Catholic Church as well as those of Anabaptists and 'strict' Gnesio-Lutherans like Tilemann Heshusius (recently elevated to general superintendent of the university) and Matthias Flacius, who were resisting Frederick's Reformed influences, particularly on the matter of the Eucharist.

The Catechism based each of its statements on Biblical source texts (although some may call them 'proof-texts' which can have a negative connotation), but the 'strict' Lutherans continued to attack it, the assault being still led by Heshusius and Flacius. Frederick himself defended it at the 1566 Diet of Augsburg as based in Scripture rather than based in Reformed theology when he was called to answer to charges, brought by Maximilian II, of violating the Peace of Augsburg. Afterwards, the Catechism quickly became widely accepted.

A synod in Heidelberg approved the catechism in 1563. In the Netherlands, the Catechism was approved by the Synods of Wesel (1568), Emden (1571), Dort (1578), the Hague (1586), as well as the great Synod of Dort of 1618–19, which adopted it as one of the Three Forms of Unity, together with the Belgic Confession and the Canons of Dort. Elders and deacons were required to subscribe and adhere to it, and ministers were required to preach on a section of the Catechism each Sunday so as to increase the often poor theological knowledge of the church members. In many Reformed denominations originating from the Netherlands, this practice is still continued.

While the catechism's introduction credits the "entire theological faculty here" (at the University of Heidelberg) and "all the superintendents and prominent servants of the church" for the composition of the Catechism, Zacharius Ursinus (1534–1583) is commonly regarded as the catechism's principal author. Caspar Olevianus (1536–1587) was formerly asserted as a co-author of the document, though this theory has been largely discarded by modern scholarship. Johann Sylvan, Adam Neuser, Johannes Willing, Thomas Erastus, Michael Diller, Johannes Brunner, Tilemann Mumius, Petrus Macheropoeus, Johannes Eisenmenger, Immanuel Tremellius and Pierre Boquin are all likely to have contributed to the Catechism in some way. Frederick III himself wrote the preface to the Catechism and closely oversaw its composition and publication.

Ursinus was familiar with the catechisms of Martin Luther, John Calvin, Jan Łaski and Leo Jud and was therefore likely influenced by them, however the Catechism does not betray a patchwork nature but a unity of style. There are three major scholarly traditions identifying the primary theological origin or influences of the Catechism: the first as 'thoroughly Calvinistic' or associated with the Genevan Reformation, the second as Reformed in the spirit of the Zurich Reformation and Heinrich Bullinger and the third as equally Reformed and Lutheran (especially Melanchthonian). The third tradition is justified by the fact that Frederick III himself was not thoroughly Reformed, but in his life represented a shift from a "Philippist/Gnesio-Lutheran theological axis to a Philippist-Reformed theological axis", which was especially evident in his attraction to the Reformed position on the Eucharist during a formal debate of 1560 between Lutheran and Reformed theologians in Heidelberg, as well as by the fact that the theological faculty which prepared the Catechism consisted of both Reformed and Philippist Lutheran figures. A proponent of this tradition, Lyle D. Bierma, also argues for this by pointing out that the theme of 'comfort' (evident in the famous first Question), is also present in works of Luther and Melanchthon which were significant in the Reformation of the Palatinate.

In its current form, the Heidelberg Catechism consists of 52 sections, called 'Lord's Days', to be taught on each Sunday of the year, and 129 Questions and Answers. After two prefatory Questions (Lord's Day 1), the Catechism is divided into three main parts.

This part consists of the Lord's Day 2, 3, and 4 (Questions 3-11), discussing the following doctrines.