Who is "the Adversary of all Evil" in Dante's "Inferno"?

Question

What's the meaning of "the Adversary of all Evil" in line 16 of Canto 2 of Inferno by Dante Alighieri, translated by John Ciardi? Here's the context (lines 13–24):

You sang how the father of Sylvius, while still
in corruptible flesh won to that other world,
crossing with mortal sense the immortal sill.

But if the Adversary of all Evil
weighing his consequence and who and what
should issue from him, treated him so well

that cannot seem unfitting to thinking men,
since he was chosen father of Mother Rome
and of her Empire by God’s will and token.

Both, to speak strictly, were founded and foreknown
as the established Seat of Holiness
for the successors of Great Peter’s throne.

Answer 1

It's God. If you consult a commentary, they should all attest to that fact. You could also find the reference in Andrew Pinsent's The History of Evil in the Medieval Age: 450-1450 CE (Routledge: 2018).

You probably don't see many comments on it because it's obvious. There's only one being in Dante's religion that could be described as being without any evil at all, who is opposed to all evil, that's the supreme deity.