The medieval church saw a vital connection between heaven and earth, with heaven being the pattern for earthly activity. “Thy kingdom come; Thy will be done on earth as it is in heaven” (Matt. 6:5–15). The eternal serves as a standard for the temporal. The Creator outlines parameters for living for the creature.
Central was the assumption of a coherence between heaven and earth, two parts of one homogeneous world, built to a single plan and hence reciprocally related, yet based on a principle of inequality inherent in hierarchy, in which the superior serves as a model for the inferior. 
Without the heaven/earth connection, the world is assigned to the realm of indifference and the inevitabilities of evil. The Lutheran and Calvinistic arms of the Reformation viewed the possibility of social change differently:
Luther had regarded this world and its institutions as incorrigible, and was prepared to leave them to the devil. But for Calvin this world, created by God, still belonged to Him; it remained potentially His kingdom; and every Christian was obliged to devote his life to make it so in reality by reforming and bringing it under God’s law. 
Calvin’s comprehensive approach to life was carried to France, England, Scotland, Italy, Germany, and the Netherlands by refugee pastors who came to Geneva to study in what John Knox described as “the most perfect school of Christ that ever was on the Earth since the days of the Apostles.”  “So while Lutheranism was confined to parts of Germany and Scandinavia, Calvinism spread into Britain, the English-speaking colonies of North America, and many parts of Europe.”  The Puritan tradition, and the tradition of American evangelicalism, is the legacy of Calvinism. 
“When our Lord Jesus appeared,” Calvin declared, “he acquired possession of the whole world; and his kingdom was extended from one end of it to the other, especially with the proclamation of the Gospel. . . . God has consecrated the entire earth through the precious blood of his Son to the end that we may inhabit it and live under his reign.” This meant that religious reform pointed also to the reform of the secular realm. “We must not only grieve for the offenses committed by unbelievers,” Calvin warned, “but also recognize that we remain unworthy to look upon heaven until there is harmony and unanimity in religion, till God is purely worshipped by all, and all the world is reformed.” Believers “truly worship God by the righteousness they maintain within their society.” 
The Pilgrim/Puritan Legacy
The Pilgrims and Puritans have gotten a lot of bad press. Some of it they deserve. Of course, I’m sure that few of us would want to be scrutinized as thoroughly as the Puritans have been. There would be a number of condemnations among the accolades. But on the whole, the Puritan legacy is a remarkably emulative heritage. Few critics fully appreciate the historical circumstances in which the Puritans found themselves. But this is not a study of Puritanism. Rather, it’s a study of how Christians, Puritans included, understood the relationship between Christianity and the world.
Social reform and evangelism went together prior to the Civil War in America and continued to the close of the nineteenth century. Of course, the impetus for reform in America pre-dates the founding of our nation. William Bradford’s History of Plymouth Plantation is an eye-witness account of the kingdom application of the gospel that motivated our nation’s earliest settlers: “A great hope and inward zeal they had of laying some good foundation, or at least to make some way thereunto, for the propagating and advancing the Gospel of the Kingdom of Christ in those remote parts of the world; yea, though they should be but even as stepping stones unto others for the performing of so great a work.” 
The relationship between gospel and society can best be seen in how our nation’s founders appreciated education, and how education was conceived as a way to preserve the Christian past and the establishment of a Christian future. Harvard College (founded in 1636, six years after the arrival of the British Puritans to New England and named after John Harvard), set the agenda for the nation’s future: “Let every Student be plainly instructed, and earnestly pressed to consider well, the main end of his life and studies is, to know God and Jesus Christ which is eternal life (John 17:3) and therefore lay Christ in the bottom, as the only foundation of all sound knowledge and Learning.”
Those who conceived and built Harvard wanted the Puritan legacy to continue. First the change of the heart in the application of the gospel; second, the change of society by men who have changed hearts: “One of the next things we longed for, and looked after was to advance Learning and perpetuate it to Posterity; dreading to leave an illiterate Ministry to the Churches, when our present Ministers shall lie in the Dust.” Why an educated ministry? Ministers were often the only source of education in the colonies. “No other thinker had such as wide audience as did the preacher in his pulpit, and his printed sermons and treatises were the staple reading matter of his parishioners.” 
The Reformation of Manners
There were similar expressions of evangelical reform in England. We should expect this, since America’s penchant for reform was inherited from its theological English forbears. For example, England’s abolition movement was almost entirely led by the evangelical wing of the church. At the pleading of Lady Middleton and Bishop Porteus, James Ramsay wrote a long Essay on the Treatment and Conversion of Slaves in the British Sugar Colonies (1784). Ramsay was “convinced that men will not respond to lessons of eternal redemption from those who enslave them on earth, or about heaven when kept in hell…. He proposed steps to total Emancipation, and suggested that free labour would yield more profit to plantation owners.” 
Too many Christians have reduced the breadth and depth and power of the Faith once for all delivered to the saints. Unwittingly, they have offered the Church a shrunken and truncated version of the Gospel that has allowed foreign worldviews to supplant what Christians should be accomplishing.
William Wilberforce, upon being struck with the oppression of the slave trade, wrote in his diary, “Almighty God has set before me two great objectives: The abolition of the slave trade and the reformation of manners.”  Had the British government “not been in the hands of Christians there seems little reason to have expected it to mount its massive, expensive, and voluntary campaign against slavery.”  If modern anti-reformists had their way, the institution of slavery would still be with us. They would be preaching to the Church to remain silent on the issue and not to mix Church and State.
America had its social reform advocates as well. As in England, nearly every theological tradition took up the banner of reform, from revivalist to seminary professor. Charles Finney, best known as a revivalist preacher, saw an obvious relationship between evangelism and the “reformation of manners,” that is, social reform. John Stott writes about Finney’s views on social reform.
Social involvement was both the child of evangelical religion and the twin sister of evangelism. This is clearly seen in Charles G. Finney, who is best known as the lawyer turned evangelist and author of Lectures on Revivals of Religion (1835). Through his preaching of the gospel large numbers were brought to faith in Christ. What is not so well known is that he was concerned for ‘reforms’ as well as ‘revivals.’ He was convinced, as Donald W. Dayton has shown in his Discovering an Evangelical Heritage, both that the gospel ‘releases a mighty impulse toward social reform’ and that the church’s neglect of social reform grieved the Holy Spirit and hindered revival. It is astonishing to read Finney’s statement in his twenty-third lecture on revival that ‘the great business of the church is to reform the world…. The Church of Christ was originally organised to be a body of reformers. The very profession of Christianity implies the profession and virtually an oath to do all that can be done for the universal reformation of the world.’ 
Finney saw no contradiction between preaching the gospel and social reform: “The Christian church was designed to make aggressive movements in every direction—to lift up her voice and put forth her energies against iniquity in high and low places—to reform individuals, communities, and government, and never rest until the kingdom . . . shall be given to the people . . .—until every form of iniquity shall be driven from the earth.”  In a footnote, George Marsden informs his readers that “Letters on Revivals—No. 23,” from which the above quotation is taken, is “left out of modern editions of these letters.”