Sentence:  Independence Day <WSD>is</WSD> the appropriate date as a symbolical reminder of the American article of faith that governments are instituted among men to secure to them certain inalienable rights , the first of which is life , and when any government becomes subversive of that end , it is the right of the people to alter or abolish it . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)