Whenever Arminianism loses its evangelical way, it is always in a “Pelagianizing” direction. Nevertheless, it is important to state the actual views that people hold rather than the views that we think they should hold or will hold if their logic is followed consistently. The crucial difference between Arminianism and Semi-Pelagianism is that the former insists upon the necessity of grace prior to all human response. At least as Arminius taught it, Arminianism does not deny original sin or the inability of human beings to save themselves. Nevertheless, Arminians do hold that sufficient prevenient grace is given to all people to exercise their free will, and election is based on God’s foreknowledge of those who will in fact cooperate with this grace in faith and good works. Final salvation is dependent to some extent on one’s cooperation with God’s grace.
Arminians themselves affirm that “synergism” is the appropriate term for this system’s view of salvation. However, Roger Olson distinguishes helpfully between “evangelical Arminians” (of the heart) and “liberal Arminians” (of the head). Representing the latter, Phillip Limborch (1633-1712) taught that the fall perverted our mind but not our will. Historically, liberal Arminianism usually merged into Socinianism (see below) or what we know as Unitarian Universalism. A more evangelical Arminianism is represented among Anglicans like Jeremy Taylor, William Law, and John Wesley and some non-Conformist Puritans like Richard Baxter and John Goodwin.
The Calvinist-Arminian divide is evident not only between Protestant denominations, but cuts across them as well: General Baptists, influenced by Mennonite communities, often in a more explicitly Semi-Pelagian directions, and Calvinistic Baptists (see the London/Philadelphia Confession of 1644); Wesleyan and Calvinistic Methodists (the latter following George Whitefielf); Old School and New School Presbyterians (the latter following Nathaniel Taylor and Charles Finney).
Going well beyond Arminianism, radical Protestantism generated another position that is important to mention. Named after Laelius Socinus (d. 1562), Socinianism not only denied God’s predestination, but also God’s exhaustive foreknowledge of the free actions of creatures, which Arminians and Calvinists both affirmed. As the fountainhead of Unitarianism, the Socinian movement also denied the Trinity and the deity and preexistence of the Son. Therefore, Socinianism represented a revival of Pelagian and Arian heresies. Through the energetic efforts of Laelius’s nephew Faustus (d. 1604), the tenents of Socinianism became widely influential in the thinking of [Issac] Newton, Locke, Voltaire, Lessing, Kant, and other Enlightenment figures. (33-34)
Taken from “For Calvinism” by Horton. Added [Issac] for clarification.