So I can’t believe this didn’t strike me until just now, but this is how these things go sometimes I guess *shrugs*
Anyway, in the book, when Strange is learning about the Johannites from Sir Walter you come to a footnote about the various false Raven Kings that have risen up over the centuries, and among them is mentioned the Summer King, who apparently “taught his followers to revere nature and wild creatures -- a creed which seems closer to the teachings of the twelfth century magician, Thomas Godbless, than anything the Raven King ever proposed.”
I’ve always had a bit of trouble trying to knot out how exactly Thomas Godbless (and the Summer Kings’s) approaches to magic and their relationship with it were different from the Raven King’s own views, especially as magic is shown to be so much reliant on nature and the spirits and beings that reside within it. Shouldn’t Thomas Godbless and the Raven King have similar approaches in that case?
But no, the answer really is there, spelled out in the text. Thomas Godbless reveres nature. It is something to be emulated, looked upon as greater than oneself. He recognizes the need to respect nature, as it is at the center of magic -- but in revering it, Thomas Godbless places it on a pedistal, above himself. You might make a request of something or someone you revere, but you don’t expect to be treated on equal terms with it. There is a knowledge there that anything done on your account is only done by the other being’s good grace. And in doing that, Thomas Godbless also sperates himself from nature, placeing it apart from himself.
Meanwhile, the Raven King had grown up in Faerie, has lived his entire life amongst Fairy Courts and Kingdoms -- before he’d even gotten to England, he’d clawed himself up onto his own throne in Faerie. He would regard nature and view magic in much the same way that Fairies do. He doesn’t revere nature, because he sees himself on an equal footing with it. A Treaty? and Alliance? These are means of sorting out power, political tools meant to sort out relationships where both parties are expecting to be gaining something, and that is how Fairies relate to nature and magic, that is how John Uskglass relates to nature and magic. A Magician -- A Person-- in the Raven King’s view isn’t outside of Nature but very much a part of it. Magic is a form of politics to him, and a King and an Oak Tree can very much be on the same level for him.