James Burgh Explains His Arianism

James Burgh, a British Whig who greatly influenced America's Founders, explained his unitarianism of the Arian variety in Crito, Volume I, here.  A taste [I have added paragraph breaks for clarity]:

.... The orthodox, who think they believe the Messiah to be God, can have no doubt of SATAN's being brought into existence by him. The Socinians, who hold the Messiah to have had no existence till he was born, cannot allow the fact, of Satan's owing either existence, or any material advantage, to the Messiah. The Unitarians can conceive of the Messiah's having been, sano senso*, the maker of this world, and likewise of the angelic orders, both those who have stood and who have fallen.

But neither do all unitarians understand in the same manner the Messiah's making worlds and their inhabitants.  It is certain, that all existence is derived from the one Supreme, to whom existence is natural, and necessary, himself the Fountain of being.  Therefore, whenever the power of making, or creating is ascribed to any subordinate being, it is manifest, the meaning cannot be, the giving of existence. 

It is to be supposed, that none, but Himself, has the power of causing that to be, which does not naturally exist.  And nothing exist naturally, but the supreme, indivisible, unequalled, and all perfect Monad. 

The Scripture writers, having never subscribed the Athanasian creed, though a good sort of clergymen, in their little way, do everywhere represent our illustrious Deliverer as subordinate to the Almighty, whom they style his God and Father.  With submission to our church's "authority[] in matters of faith", I beg leave to propose to the reader's consideration, whether He, whose God the Father[] the Almighty is, can be properly said to be the Almighty; whether the Almighty has a God and Father; or whether the Son of God is the Father of the Son of God. 

If not, then it is easy enough to understand, that the creating, or making of the grand Enemy may signify nothing more, than that the Messiah was he, who originally introduced the whole species of angels, not into existence, but into that advantageous state and contrition, which enabled them to become, in process of time, angels.

Now, it does not, as far as I can perceive, necessarily follow from the Messiah's having been, in the sense here explained, the Maker of Satan (and I own I cannot conceive of his having been so in any higher sense) ....

*Rowe:  I had to transcribe this term.  I'm not sure what it means.

So Burgh apparently believed in a kind of Arianism where Jesus is the firstborn of all creation, higher in power than the highest archangel, but lower than God.  As to the rest, I understand it as Burgh asserting that God the Father (not Jesus) causes all clay to come into existence; but Christ was given a great deal of authority to shape that clay into finished works.