Thesis question

I was just wondering if anyone could help me out with forming a thesis? The essay has to be a historical criticism on a chosen text (I chose Oedipus Rex). Basically, it has to be an essay stating how the text was a product of the times it was written.

Oedipus Rex was written during the Ancient Greece era, so they believed Gods governed our fate. I can make a thesis out of the latter part of the sentence, but I have no idea how to include the historical context.

This is what I have:
Influenced by Ancient Greece’s belief in predetermination, Oedipus Rex emphasizes the fact that fate is inescapable.

It sucks, but I'll re-do it later. I'm having trouble connecting the pieces, and maybe the general thesis as well. I feel like it's weak, or just doesn't fit right. I've tried googling up, "how to write a thesis" but nothing sticks.