Yes, I think so. At the very end of the novel, Golding has Ralph break down in front of the naval officer.
And in the middle of them, with filthy body, matted hair, and unwiped nose, Ralph wept for the end of innocence, the darkness of man’s heart, and the fall through the air of the true, wise friend called Piggy.
'The darkness of man's heart'. This is the central theme of the book: and Golding's argument is exactly the same as Simon's when he stutteringly tries to express what he thinks about the beast at one of the early assemblies:
“What I mean is. . . maybe it’s only us.”
That was from Piggy, shocked out of decorum. Simon went on.
“We could be sort of. . . ”
Simon became inarticulate in his effort to express mankind’s essential illness. Inspiration came to him.
“What’s the dirtiest thing there is?”
Mankind's essential illness. The darkness of man's heart. It is a central question, and the central believability question of the novel: do you believe that a group of boys, crashed onto an island, would end up behaving like this? Would there really be deaths? Is this novel plausible?
If you think, 'yes', do you blame it, like Golding, on an evil, a devil, inherent in all human beings - even in Ralph, who has eyes that 'proclaimed no devil'? Or is it more to do with the culture of war from which the boys come? Why is it that things break up like they do?
In modern times, we still have the same question. Are humans really evil? Are suicide bombers born bad - or is it cultural? Nature or nurture? Darkness of man's heart - or darkness of our world?
I think it's a really pertinent theme in modern times.