The PC(USA)

History

Presbyterians trace their history to the 16th century and the Protestant Reformation. Our heritage, and much of what we believe, began with the French lawyer John Calvin (1509-1564), whose writings crystallized much of the Reformed thinking that came before him.
Calvin did much of his writing from Geneva, Switzerland. From there, the Reformed movement spread to other parts of Europe and the British Isles. Many of the early Presbyterians in America came from England, Scotland and Ireland. The first American Presbytery was organized at Philadelphia in 1706. The first General Assembly was held in the same city in 1789. The first Assembly was convened by the Rev. John Witherspoon, the only minister to sign the Declaration of Independence.
Presbyterian denominations in the United States have split and parts have reunited several times. Currently the largest Presbyterian denomination is the Presbyterian Church (U.S.A.), which has its national offices in Louisville, Ky. It was formed in 1983 as a result of reunion between the Presbyterian Church in the U.S. (PCUS), the so-called “southern branch,” and the United Presbyterian Church in the U.S.A. (UPCUSA), the so-called “northern branch.” Other Presbyterian churches in the United States include the Presbyterian Church in America, the Cumberland Presbyterian Church and the Associate Reformed Presbyterian Church.

Theology

Some of the principles articulated by John Calvin remain at the core of Presbyterian beliefs. Among these are the sovereignty of God, the authority of the scripture, justification by grace through faith and the priesthood of all believers. What they mean is that God is the supreme authority throughout the universe. Our knowledge of God and God’s purpose for humanity comes from the Bible, particularly what is revealed in the New Testament through the life of Jesus Christ. Our salvation (justification) through Jesus is God’s generous gift to us and not the result of our own accomplishments. It is everyone’s job — ministers and lay people alike — to share this Good News with the whole world. That is also why the Presbyterian church is governed at all levels by a combination of clergy and laity, men and women alike.
Presbyterians confess their beliefs through statements that have been adopted over the years and are contained in The Book of Confessions. These statements reflect our understanding of God and what God expects of us at different times in history, but all are faithful to the fundamental beliefs described above. Even though we share these common beliefs, Presbyterians understand that God alone is lord of the conscience, and it is up to each individual to understand what these principles mean in his or her life.

The Trinity

Like all other Christians, Presbyterians believe that the doctrine of the Trinity affirms the oneness of God. The Old Testament bears witness to this; "The Lord is our God, the Lord alone?" (Deuteronomy 6:5), and "I am the Lord your God . . . you shall have no other gods before me." (Exodus 20:2-3). Also, in the New Testament, we read, "There is no God but one?" (1 Corinthians 8:4). "Make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit." (Matthew 28:19)

Presbyterians believe that the doctrine of the Trinity also affirms the Father, the Son, and the Holy Spirit as distinct persons who reveal themselves as God.  Many passages from the New Testament mention the Father, Son (or Jesus Christ), and Holy Spirit as co-equals in the work of God. Presbyterians, like other Christians, believe that there is but one God and that the doctrine of the Trinity reaffirms this belief. Accordingly, while the Father, Son, and Holy Spirit are three distinguishable expressions of the one God, they are not three separate expressions of deity.

Church Government

A major contributor to Reformed theology was John Calvin, who converted from Roman Catholicism after training for the priesthood and in the law. In exile in Geneva, Switzerland, Calvin developed the presbyterian pattern of church government, which vests governing authority primarily in elected laypersons known as elders. The word presbyterian comes from the Greek word for elder.
Elders are chosen by the people. Together with ministers of the Word and Sacrament, they exercise leadership, government, and discipline and have responsibilities for the life of a particular church as well as the church at large, including ecumenical relationships. They shall serve faithfully as members of the session. (Book of Order, G-10.0102) When elected commissioners to higher governing bodies, elders participate and vote with the same authority as ministers of the Word and Sacrament, and they are eligible for any office. (Book of Order, G-6.0302)
The body of elders elected to govern a particular congregation is called a session. They are elected by the congregation and in one sense are representatives of the other members of the congregation. On the other hand, their primary charge is to seek to discover and represent the will of Christ as they govern. Presbyterian elders are both elected and ordained. Through ordination they are officially set apart for service. They retain their ordination beyond their term in office. Ministers who serve the congregation are also part of the session. The session is the smallest, most local governing body. The other governing bodies are presbyteries, which are composed of several churches, synods, which are composed of several presbyteries, and the General Assembly, which represents the entire denomination. Elders and ministers who serve on these governing bodies are also called presbyters.

Social Issues

The General Assembly “Affirms its conviction that neither the Church as the body of Christ, nor Christians as individuals, can be neutral or indifferent toward evil in the world; Affirms its responsibility to speak on social and moral issues for the encouragement and instruction of the Church and its members, seeking earnestly both to know the mind of Christ and to speak always in humility and love; Reminds the churches that their duty is not only to encourage and train their members in daily obedience to God’s will, but corporately to reveal God’s grace in places of suffering and need, to resist the forces that tyrannize, and to support the forces that restore the dignity of all men as the children of God, for only so is the gospel most fully proclaimed; ...”
—1958 Statement – PC(USA), p. 537

For more information, see:  https://www.presbyterianmission.org/what-we-believe/social-issues/