The Antithesis is what the Principle and its Princes call the equal and opposite force that stands against the Principle. The Antithesis is not its true name, which is actually either unknown or even literally unknowable to you. Just as the Principle can derive gods from itself, the Antithesis can also derive gods from itself. These are called the antithetical gods, or Adversaries.
While the Principle generally has a humane and principled mindset and goals, if often on a cosmically large and impersonal scale, the Antithesis has an alien and antithetical mindset and goals.
The Principle and the Antithesis are not capable of directly interacting, nor even drawing close to each other. You could say they are repelled from and aligned with each other like opposing magnetic poles. Both feel it is their fundamental right and obligation to have sole control over the mortal realm, Natura, that lies in the metaphysical space between the two forces. Thus, both forces derive gods from themselves that are capable of interacting directly with Natura.
Neither the Principle nor the Antithesis are omniscient, nor remotely omnipotent. They are, in a certain sense, perfect entities, as they are flawless within the terms of their own natures. But their limitations and natures also make them inflexible and unchangeable. They are more the fundamental pillars of reality then what we might think of as gods.