Presbyterians are part of the Calvinist branch of Protestantism. Calvinist teachings have been summed up in the T.U.L.I.P formula; also termed “The Five Points of Calvinism.” To firmly grasp T.U.L.I.P. is to address why the Scots-Irish viewed themselves as a Covenant People elected by God with a destiny. In American religious history, it came to define the differences between Presbyterians and Methodists.
Below is a brief explanation of T.U.L.I.P. theology. Be aware that emphasis varies depending on how liberal, moderate or conservative a theological viewpoint:
Total Depravity: Humanity is corrupt, perverse and sinful due to inborn corruption. There is nothing humans can do pertaining to their own salvation.
Unconditional Election: God elected certain individuals for salvation from before the world was created. None deserve God’s favor, and only those whom God has elected will be saved. Election is not salvation. It only marks out certain individuals for salvation. The elect must still be saved through their faith in Jesus.
Limited Atonement: God’s elect are given to the Son to be redeemed. Because of Christ’s atonement, the redeemed are counted righteous before God; freed from guilt and condemnation.
Irresistible Grace: The Holy Spirit never fails to bring to salvation elect sinners. The elect respond to the Holy Spirit’s “special inward call.” This will allow the elect sinners to understand and believe spiritual truth.
Perseverance of the Saints: Termed “once saved, always saved,” or “Eternal Security,” the elect are redeemed by Christ, and kept in faith by the power of God. They cannot lose their salvation.
More details can be found in Michael Horton’s, The Christian Faith (2011); Robert L. Reymond’s, A New Systematic Theology of the Christian Faith (1998); David N. Steel, Curtis C. Thomas and S. Lance Quinn, The Five Points of Calvinism (2004).