Homer's epic shows the freedom scene of liberalism and sets an example for the moral concept of Greeks in the future (and then for the moral concept of the whole western society). What followed was, firstly, a humanistic ethic of pursuing achievement and self-realization, and secondly, a liberal theology of the same sex between man and god, which stripped away the mysterious fear in the spiritual world. Homer's epic became the "Greek Bible". I think the topic of your thesis should be the influence of Homer's Iliad on modern European civilization.