I thought Perelandra was bizarre, almost hallucinogenic towards the end. And the bit with the devil could be read as “He’s right, so I have to resort to physical violence to win.” I found it funny, but a strange take for an author known for making intellectual arguments for Christianity.
Perelandra's devil – the Un-Man – struck me on first reading as an excellent early depiction of a hostile, alien form of intelligence, superior but purely instrumental. Lewis was very early in working out the implications of that – nowadays the Rationalists and a lot of others would agree that there can be entities with superhuman intelligence that don't intrinsically value their intelligence, and that such beings would have almost irresistible persuasive ability if given the opportunity. (Lewis differs in also giving the Un-Man genuinely supernatural abilities with which it attempts to overawe the protagonist.)
"it regarded intelligence simply and solely as a weapon… Thought was for it a device necessary to certain ends, but thought in itself did not interest it. It assumed reason… externally and inorganically…"
Ransom doesn't concede the Un-man is right. Rather, he concedes that the Un-man has unlimited intellectual stamina, so in any debate with a human, the human eventually succumbs to his persuasion because humans reason imperfectly.
Published in 1943, when the cultural milieu of Britain had had to process the results of appeasement and was forced to fight Hitler - a leader many of them actually not-so-secretly admired. For British intellectuals, WWII in many ways meant conceding an ideological point to Nazism (when chips are down, all that matters is actual raw strength, rather than the post-WWI rhetoric of peace) while fighting to defeat it.
