"The Socinians are the real forerunners of process theology, and indeed almost of process philosophy generally."

     Charles E. Hartshorne, Aquinas to Whitehead:  seven centuries of metaphysics of religion, Aquinas lecture 1976 (Milwaukee, WI:  Marquette University Publications, 1976), 14.  I was put onto this by Leo Scheffczyk, "Prozeßtheismus und christlicher Gottesglaube," Münchener theologische Zeitschrift 35, no. 2 (1984):  100 (81-104).  I have not yet examined it in context, though the discussion of Socinianism begins on p. 13.