Revelation mentions a star falling to earth in the time of the end and it is called Wormwood. What is this Wormwood?

At Revelation 8:11, wormwood denotes a bitter and poisonous substance.
The star called wormwood fell from heaven (a high position where it could serve as a guide to men and steer them to refreshing waters of life) and down into a third of the rivers and water fountains, thus making a third of the fresh waters bitter like wormwood, so much so that "many of the men" died from drinking them. In its being a fallen "star" and being able to affect the drinking water of possibly a third of the men disastrously, this "star" named Wormwood pictured the religious clergy of Christendom, whose population embraces "many of the men," about a third of earth's population.

This "wormwood" refers to those claiming to be a Christian clergy ordained by God as ministers, but who are actually apostate religious leaders, produced by apostate religious systems. Like a star in the sky it should have beamed down heavenly or spiritual light upon the people of Christendom, guiding them to the refreshing waters of Christian truth found in the Bible, and to a course in life in harmony with those Bible truths; however, these apostate religious leaders have taught their church people religious doctrines that have been bitter to their spiritual taste, adulterating God's Word with pagan doctrines or exalting the traditions of uninspired men above the Bible.