Outside Movie - Taxi Driver - Robbie Heath

Taxi Driver is a classic but more of a cult classic by Martin Scorsese. In this film the main character, played by Robert DeNiro ends up going on a violent spree. At the surface this film does not seem to have a deeper meaning. However, unlike many films made today, the violence actually has a reason behind it. DeNiro's character is not mean and hurtful for the sake of it. Rather his violence is done in a bout to protect a young girl that was put into prostitution. In addition it is his form of bringing justice to those that would not receive it. These are people like the pimps and drug dealers of New York that he went after. It seems that this violence as it is in other Scorsese films like The Departed, is justified in some way. It is more of a righteous wrath and anger like the anger found in the God of the Old Testament. In this anger there is a wrath towards what is sinful in God's eyes. This is similar to the wrath found in Taxi Driver, it goes towards what is detestable and sinful. Does this seem correct? Or is violence never justified?