What's More Effective: Good vs Evil or Reformed Evil vs. Evil?

Who is more effective at fighting Evil: He who is as pure as possible and avoids all things evil or He who knows or once was evil but repented?

It seems to me that he who has known evil would have the upper hand because he better understands the enemy and can see the enemy’s moves in advance. However, the one who is pure would be stronger to resist temptations into evil activities or thoughts.

For example, would an undercover narcotics cop be more effective if he occasionally partakes of the drugs he is “selling” or “buying”. Would it not give him more credibility and allow him to move farther up the chain of command he wishes to bring down? The downside is the danger of drug addiction.

How about the FBI Agent who specializes in catching serial murderers? By delving into their sordid interests, whether it be child pornography, necrophilia, website murder sites, etc., enable them to better formulate a strategy to catch them? The downside is him becoming “creepy” or worse.

What about priests who perform exorcisms? Should not priests read books about Satanism and other negative energy texts to better understand the lure of evil? Wouldn’t that allow them to better anticipate the demonic twists that would come their way during a possession (I’m assuming you believe in that sort of thing).

On a more mundane level, what kind of preacher has more on an impact on you: the one who has lived as good as life as possible or the one who lived a life of sin, suffered and repented? I think you can relate better to the sinful one but can really respect the good one.

The thing that got me thinking about this was “Dante’s Inferno” or, rather, a book based upon it called “Inferno”. In this book, an average guy dies and wakes up in a version of Dante’s Inferno in which he must travel through the Nine Levels of Hell in order to escape it. Along the way, he suffers and sees suffering but ends up a changed man. It got me thinking that, perhaps, the way to Heaven is to go through Hell. I’ve certainly done that in my life and the thought keeps me hoping that my suffering will amount to something good in the end.

So, besides my first question of whether or not being evil equips you better to fight evil, another related question is raised: Is becoming evil or understanding evil justifiable in combatting evil?

Response to several points:

  1. According to Christian doctrine, everyone is innately sinful. So excepting Jesus himself and the angels, all “good” people are Reformed Evil.

  2. Good is not synonymous with innocent or naive. In fact good people probably understand the real nature of evil better than those immersed in it.

  3. A narcotics officer who uses drugs would not qualify for the “Reformed” part in my opinion.

  4. Certainly people like police officers and priests need specialized knowledge of many things that are unsavory.

  5. Without getting into a boatload of theology about why evil exists and God’s purpose in redemption, it would be better for evil to not exist at all. Goodness doesn’t need evil.