Calvin's epistle to the reader indicates that the new work is intended for theological students preparing for ministry. It includes many references to classical authors and Church fathers, as well as many additional references to the Bible. In 1539, Calvin published a much larger work, with seventeen chapters of about the same length as the six chapters of the first edition. The Institutes proved instantly popular, with many asking for a revised edition. Soon after publishing it, Calvin began his ministry in Geneva, Switzerland. It is six chapters long, covering the basics of Christian creed using the familiar catechetical structure of the Ten Commandments, the Apostles' Creed, the Lord's Prayer, and the sacraments, as well as a chapter on Christian liberty and political theology. The work, written in Latin, was published in Basel in March 1536 with a preface addressed to King Francis I of France, entreating him to give the Protestants a hearing rather than continue to persecute them. He decided to adapt the work he had been writing to the purpose of defending Protestants suffering from persecution from false accusations that they were espousing radical and heretical doctrines. His Catholic opponents sought to tie him and his associates (known as Huguenots in France) to groups of radical Anabaptists, some of which had been put down by persecution. He moved to Basel, Switzerland, for safety in 1535, and around this time he must have begun writing a summary of theology which would become the Institutes. Around 1533 he became involved in religious controversies and converted to Protestantism, a new Christian reform movement which was persecuted by the Catholic Church in France, forcing him to go into hiding. John Calvin was a student of law and then classics at the University of Paris. The Institutes is a core reference for the system of doctrine adopted by the Reformed churches, usually called Calvinism. It vigorously attacked the teachings of those Calvin considered unorthodox, particularly Roman Catholicism, to which Calvin says he had been 'strongly devoted' before his conversion to Protestantism. The book was written as an introductory textbook on the Protestant creed for those with some previous knowledge of theology and covered a broad range of theological topics from the doctrines of church and sacraments to justification by faith alone and Christian liberty. Regarded as one of the most influential works of Protestant theology, it was published in Latin in 1536 (at the same time as Henry VIII of England's Dissolution of the Monasteries) and in his native French language in 1541, with the definitive editions appearing in 1559 (Latin) and in 1560 (French). Institutes of the Christian Religion ( Latin: Institutio Christianae Religionis) is John Calvin's seminal work of systematic theology.

The title page from the fifth and final 1559 edition of John Calvin's Institutio Christianae Religionis ( Calvin, 1559, France)

Calvin institute of christian worship