>>Unitarianism began in the 16th century and arose from the Anabaptist movement and its radical interpretation of Sola Scriptura.
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This is one tenth right. Yes unitarianism branched from Poland into england.
However, it gained legitimacy in the english speaking world through Issac Newton. Who was a fervid believer in the arian heresy...why? because it was the logical outcome of cartesian logic. He was a prolific writer on the subject. Because Newton was considered to be something of a demigod in the English speaking world—the brightest minds for nearly two hundred year figured if the master believed that Jesus was just a man — it must be so. Heck you can find Newton referred to in theological tracts of the 19th century.
However, that’s just the English speaking world. Descartes made his way to the continental religious thinking through the higher criticism school. This school treated the bible as a myth like greek myths or norse myths. If you examine all miracles including those of Moses and Jesus as myths then of course mana from heaven are perhaps quail. And of course Jesus is just a man.
The higher criticism school took over the protestant seminaries in Europe in the 1850’s (at the same time the atheists took over the philosophy departments there.) The higher criticism school made the crossing to American liberal seminaries as early as the 1890’s but didn’t fully take them over until the 1940’s.
In the catholic church, Arianism shows up among progressive catholics in the guise of Liberation theology which both Pope John Paul II and Benedict have strongly opposed
But Sola Scriptura paved the way fro Decartes by elevating the individual’s conscience over understanding the Bible rather than the Pope or the Catholic Church.
Fr. John Whiteford, a convert Russian Orthodox priest observes, about Sola Scriptura and Descartes.
Protestant scholars (both “liberals” and “conservatives” have erred in that they have misapplied empirical methodologies to the realm of theology and biblical studies. I use the term “Empiricism” to describe these efforts. I am using this term broadly to refer to the rationalistic and materialistic worldview that has possessed the Western mind, and is continuing to spread throughout the world. Positivist systems of thought (of which Empiricism is one) attempt to anchor themselves on some basis of “certain” knowledge. 11 Empiricism, strictly speaking, is the belief that all knowledge is based on experience, and that only things which can be established by means of scientific observation can be known with certainty. Hand in hand with the methods of observation and experience, came the principle of methodological doubt, the prime example of this being the philosophy of Rene Descartes who began his discussion of philosophy by showing that everything in the universe can be doubted except ones own existence, and so with the firm basis of this one undoubtable truth (”I think, therefore I am”) he sought to build his system of philosophy. Now the Reformers, at first, were content with the assumption that the Bible was the basis of certainty upon which theology and philosophy could rest. But as the humanistic spirit of the Enlightenment gained in ascendancy, Protestant scholars turned their rationalistic methods on the Bible itself—seeking to discover what could be known with “certainty” from it. Liberal Protestant scholars have already finished this endeavor, and having “peeled back the onion” they now are left only with their own opinions and sentimentality as the basis for whatever faith they have left.
http://orthodoxinfo.com/inquirers/tca_solascriptura.aspx
One could also argue that Protestantism is a subset of Nominalism, which had an equal influence on Decartes, as the following essay on the consequences of the Protestant Revolution:
Eventually, the philosophy of Ockham led to the Rationalism of Rene Descartes and Goffried Leibnitz; it would find its logical conclusion in the Pantheism of Baruch Spinoza; and it would greatly contribute to the uprise of Social Materialism (modern capitalism) as formulated by John Locke, David Hume, and Auguste Comte. Further, we know that John Locke became a great influence on the thinking of such philosophic “giants” as Adam Smith and John Stuart Mill of England, as well as Voltaire and Jean Jacques Rousseau of France. 29