The theological tensions within the denomination were played out in the Fundamentalist–Modernist Controversy of the 1920s and 1930s, a conflict that led to the development of Christian fundamentalism and has historical importance to modern American evangelicalism.

Drawing from the Scotch-Irish revivalist tradition, evangelical ministers such as William and Gilbert Tennent emphasized the necessity of a conscious conversion experience and the need for higher moral standards among the clergy.

[22] After the Battles of Lexington and Concord, the Synod of New York and Philadelphia published a letter in May 1775 urging Presbyterians to support the Second Continental Congress while remaining loyal to George III.

One of the results was that the PCUSA signed a Plan of Union with the Congregationalists of New England in 1801, which formalized cooperation between the two bodies and attempted to provide adequate visitation and preaching for frontier congregations, along with eliminating rivalry between the two denominations.

[33] The proliferation of voluntary organizations was encouraged by postmillennialism, the belief that the Second Coming of Christ would occur at the end of an era of peace and prosperity fostered by human effort.

The most famous camp meeting of the Second Great Awakening, the Cane Ridge Revival in Kentucky, occurred during a traditional Scottish communion season under the leadership of local Presbyterian minister Barton W. Stone.

[41] Meanwhile, the Cumberland Presbytery, also within the Kentucky Synod, faced a shortage of ministers and decided to license clergy candidates who were less educated than was typical and who could not subscribe completely to the Westminster Confession.

The New England theology modified and softened traditional Calvinism, rejecting the doctrine of imputation of Adam's sin, adopting the governmental theory of atonement, and embracing a greater emphasis on free will.

[50] The Synod of Philadelphia and New York had expressed moderate abolitionist sentiments in 1787 when it recommended that all its members "use the most prudent measures consistent with the interests and state of civil society, in the countries where they live, to procure eventually the final abolition of slavery in America".

Later, the General Assembly called slavery "a gross violation of the most precious and sacred rights of human nature; as utterly inconsistent with the law of God".

In May, the Old School General Assembly passed the controversial Gardiner Spring Resolutions, which called for Presbyterians to support the Constitution and Federal Government of the United States.

[56] In response, representatives of Old School presbyteries in the South met in December at Augusta, Georgia, to form the Presbyterian Church in the Confederate States of America.

Such fears were prompted in part by heresy trials (such as the 1874 acquittal of popular Chicago preacher David Swing) and a growing movement to revise the Westminster Confession.

Utilizing comparative linguistics, archaeology, and literary analysis, German proponents of high criticism, such as Julius Wellhausen and David Friedrich Strauss, began questioning long-held assumptions about the Bible.

[61] While Briggs held to traditional Christian teaching in many areas, such as his belief in the virgin birth of Jesus, conservatives were alarmed by his assertion that doctrines were historical constructs that had to change over time.

In 1891, Briggs preached a sermon in which he claimed the Bible contained errors, a position many in the church considered contrary to the Westminster Confession's doctrines of verbal inspiration and Biblical inerrancy.

The 1891 General Assembly vetoed his appointment to Union Theological Seminary's chair of Biblical studies, and two years later Briggs was found guilty of heresy and suspended from the ministry.

The Deliverance reasserted the church's belief in biblical inerrancy and required any minister who could not affirm the Bible as "the only infallible rule of faith and practice" to withdraw from the Presbyterian ministry.

[64] In the twentieth century, Presbyterian and Episcopalians tended to be wealthier and more educated (having more graduate and postgraduate degrees per capita) than most other religious groups in the United States,[65] and were disproportionately represented in the upper reaches of American business,[66] law, and politics.

[67] The Boston Brahmins, who were regarded as the nation's social and cultural elites, were often associated with the American upper class, Harvard University;[68] and the Episcopal and the Presbyterian Church.

[72] Briggs' heresy trial was a setback to the movement for confessional revision, which wanted to soften the Westminster Confession's Calvinistic doctrines of predestination and election.

[61] While overwhelmingly approved, the reunion caused controversy within the PCUSA due to concerns over doctrinal compatibility and racial segregation in the Cumberland Presbyterian Church.

According to church historian Bradley Longfield, Stelzle "advocated for child-labor laws, workers' compensation, adequate housing, and more effective ways to address vice and crime in order to advance the kingdom of God.

The presbytery's action was appealed to the 1910 General Assembly, which then required all ministry candidates to affirm five essential or fundamental tenets of the Christian faith: biblical inerrancy, the virgin birth, substitutionary atonement, the bodily resurrection, and the miracles of Christ.

[81] A month later, the presbytery licensed two ministers who could not affirm the virgin birth, and in February 1924, it acquitted Fosdick who subsequently left his post in the Presbyterian Church.

Attempting to deescalate the situation, General Assembly moderator Charles Erdman proposed the creation of a special commission to study the church's problems and find solutions.

Even after board members affirmed their belief in "Jesus Christ as the only Lord and Saviour", some conservatives remained skeptical, and such fears were reinforced by modernist missionaries, including celebrated author Pearl S. Buck.

When applied to biblical interpretation, Common Sense philosophy encouraged theologians to assume that people in all times and cultures thought in similar ways.

[98] From 1910 to 1927, the Confession of Faith was officially interpreted with reference to five fundamental beliefs: biblical inerrancy, the virgin birth, substitutionary atonement, the bodily resurrection, and the miracles of Christ.

It was determined that the General Assembly could not define essential beliefs without first amending the church's constitution, which allowed a greater degree of toleration for alternative interpretations of the Confession.