tragic flaw

Faust's tragic flaw was his pride. Pride is one of the Seven Deadly Sins, arguable the one that leads to all the others. Within the Christian framework, pride is a lethal motivation because it makes the sinner forget his fallen state. For Christians, men are fallen since birth, because they carry with them the taint of original sin. A men made haughty with pride forgets that he shares Eve's sin, and must therefore be saved by the gift of grace. Only God, through Christ, can dispense this grace, and the man who forgets that fact deprives himself of the path to salvation.

Faustus' first great sin is pride. He does not stop there. Reflecting the Christian view, pride gives rise to all of the other sins, and ends ironically with the proud man's abasement. Faustus goes quickly from pride to all of the other sins, becoming increasingly petty and low.