Well, one thing it would necessitate is not aiding and abetting a system to unjustly imprison people within a magophobic religious institution's iron grip. And the organization's goals, methods, and the things it tolerates are what makes it evil; how evil the individual is depends on how much they do to advance those..
Ah, and therein lies the heart of much of this debate: the moral and practical qualifications of the Circle system.
Now, being the pro-templar guy that I am, I'd state that your statements are exaggerations of what is actually the case and completely ignore to possible dangers of just placing such power people among the general population, but that would not get to the point of what I'm saying, would it?
I suppose a better point for me to make would be that organizations are simply the product of the people within them. The Templar Order is definitely an organization which one can join seeking to do good. They are meant to be protectors of the people. That is the purpose on which the order was founded. Is it so hard for you to believe that some good can be found in the Order, despite the bad?