The purpose of man versus society is to show the power of overcoming unjust government situations. It raises awareness that any man can take a stand and make a difference. Also, V's willingness to risk his life for this chosen path shows the conviction of his beliefs and values.
V takes on society believing he can change the world. With the film making judgments against the government, it implies that current systems could follow a similar course. The film raises the question of whether man versus society (or government) is vindication or terrorism.
The theme of man versus society is the core theme throughout the film. It is illustrated through several practices including the philosophical insights revealed by V, the risks he takes, and the correlation between the current government and the tyranny V must face.