As my current work leaded me to analyse existence from the systemic point of view, I've decided it's time to read Sartre and about existentialism, which I've long time postponed. So I've started with Nausea and Existentialism is Humanism.
Minutes after starting, I've found Sartre is brilliant, but for creating mental melodramas. I couldn't finish reading, despite the small truths and lovely phrases, I see a global fallacy, a rhetoric construction, the same stuff humorists do, but excluding humour. Hope being wrong and finding the vein that will help me understanding Sartre.
What I don't get is Sartre builds the full exposition body based on implicit assumptions. What is the formal definition of existence, God, (human) essence, for Sartre, for existentialists? Can anyone give me some hints about this three concepts on existentialism?