Final answer:
Thomas Paine uses a metaphor to compare the potential destruction of liberties to an overwhelming flood known as a deluge.
Step-by-step explanation:
Thomas Paine uses a metaphor in the phrase "If we omit now Massanello may sweep away the liberties of Co-Tibet like a deluge." A metaphor is a figure of speech in which a word or phrase is applied to an object or action to which it is not literally applicable. In this case, Massanello's potential to destroy liberties is compared to a deluge, which is an overwhelming flood. The use of a deluge to represent the sweeping away of liberties illustrates the devastating impact that such actions could have on a society.