Unexpected Guest

While reading Battlestar Galactica and Philosophy: Mission Accomplished or Mission Frakked Up? (gosh, what a title), some sentences make me react.
Here is my best of so far:

• Choices construct your identity: you are whom you act.
  That I agree with.
  That's why assholes will ever be assholes: there's no forgiveness for twats.
  And that's also why being a fair guy is a daily challenge.
• I choose what to post online because it is how I want to reflect myself, not because it describes the core of my being. There could even not be a stable "core of my being".
  Huh, that's at least disturbing.
  This time I do not agree at all, what I post here is what I am.
  Ah shit, now I'm invaded by doubt...
  Ok, now what was the last time I saw my stable core of my being?
• Sartre said: "existence precedes essence".
  Hey, this statement's so crystal clear that I won't comment it.
  The remaining question is, as I do exist, have I already reached the essence stage?
  (I think Jean-Paul was saying such things just because that was the way he wanted to reflect himself)
  (Poor guy, Tylenol hadn't been invented yet when he was raving this way)

So, am I what I read or do I read this book to appear the way I want?