One day in Bible Study, while discussing Atheism, I posited that Unitarianism (which believes in "everything") is the natural opposite of Atheism (which believes in "nothing"). Thoughts?
Unitarianism is an antitrinitarian heresy, beginning in the 16th century, which teaches God is one person, with no distinctness between the Father, Son and Holy Ghost. Sabellianism, on the other hand, simply taught they were different modes in one God (rather than being distinct persons in the Godhead). They believe that Jesus was a prophet and some might even say the “son” of God, but not God himself (an Arianism heresy that is followed by some Unitarians) and that Jesus was born a mere human (Psilanthropism) and, because of his greatness, “adopted” by God (Adoptionism and Socinianism followed by the non-Arianism sect of Unitarianism). They reject the doctrines of Original Sin (humanity is neither inherently corrupt nor inherently virtuous, but capable of both good and evil), predestination, eternal damnation, vicarious sacrifice for atonement, and Biblical Inerrancy (God inspired the work, but humans created errors in recording it), and also deny the virginal birth (Ebionitism). This originally started as a subset of the Anabaptism “radical reformed” movement. They believe that reason, rational thought, science and philosophy coexist with faith in God. They lean towards moderate Universalism in that they believe no one religion has a monopoly on theological truth. The Unitarian ‘church’ still exists today.