I found this via googlebooks. It examines universalism in Christendom in the modern era (modern for 1830). I plan on excerpting much more from this book. One thing that stood out was theological developments in Germany that seemed to parallel those in America and England -- what influenced America's "key" Founders.
We've heard the terms "theistic rationalism," "Christian-Deism," "Christian-unitarian-universalism," "rational Christianity" -- the mean between orthodox Christianity and Deism. The expositors of which combined both natural and revealed religion (Reason and the Bible) to arrive at this theology.
This passage on pp. 129-31 describes it in Germany along with a host of names of German theologians of whom I've never heard who believed in this:
In the latter part of this century the controversy took a still wider range. Disgusted at the errors, bigotry and arrogance of Catholics, Lutherans, and the Reformed, many of the learned in Germany turned from them in disgust: some, sickening at the name of Religion, became Atheists; others, charging upon Christianity the errors of men, took refuge in the comfortless speculations of Deism; but a third class, possessing the prudence to examine the Divine Word for themselves, saw clearly the distinction between the real and the alleged doctrines of Revelation, and asserted and maintained, with vigor and discretion, the purer system of Jesus Christ. The three principal and popular errors, which they opposed, were the doctrines of the Trinity, Atonement and Eternal Punishment.
VIII. Among these may be reckoned Gruner, Eberhard, Steinbart, Damm, Fuller, and the immortal Semler. Steinbart was teacher of divinity at Frankfort, on the Oder, and his sentiment was, to use his own words, "God can never punish any, more than is necessary for his reformation. He cannot mistake in the choice of his means, and must always reach his end. He would appear less lovely, if one creature should be forever miserable."9 He published at Zullichan the "Christian Doctrine of Happiness," in which, says the orthodox Erskine, "the unscriptural sentiments which have appeared in German books and journals, as to the divinity and atonement of Christ, are reduced to a system, with several additions of his own." Gruner, divinity-professor at Hall, in a compound of divinity, published in 1777, argues against the divinity and atonement of Christ, and the eternity of hell torments.1
This emphasis was mine. It's this "third class" which America's key Founders and the theologians and philosophers they followed could be placed in.
Update: The book is from 1830, NOT 1822 as was originally reported and the error has been corrected.