en.wikipedia.org/wiki/Lord_of_the_Flies

Standard reference works do not describe Beelzebub as “the god of pride and warfare.”

• Merriam-Webster defines Beelzebub as the devil / prince of devils, and gives the etymology as a Philistine god, literally “lord of flies.”
• Oxford reference material reproduced by Encyclopedia.com likewise says Beelzebub is a name for Satan or the Devil, with the name deriving from “lord of the flies.”
• Britannica’s overview of demonology says medieval writers associated pride with Lucifer, while Beelzebub was associated with gluttony.

So the article is mixing up different traditions. The "Lord of the Flies"/Beelzebub connection is real, but calling Beelzebub "the god of pride and warfare" is not how standard reference sources describe the figure.

This parenthetical claim is incorrect.

William Golding’s official site says Nigel Williams’s stage adaptation of Lord of the Flies was completed in 1990, that “William Golding approved this theatrical dramatisation”, and that Golding attended the premiere. That means the 1984 school production was not the only stage production endorsed by Golding.

The timing is also wrong. NobelPrize.org states that Golding died on June 19, 1993. Since Williams’s approved adaptation was completed in 1990 and premiered before Golding’s death, Golding was not already dead “by the time it was adapted again.”