Tyranny does not arrive on our doorstep, fully formed, proclaiming itself as such. Evil does not wear a black hood and cape, monologuing about "the true power of darkness!" Such things come in increments. In drips and drabs, each drab appearing unremarkable due to its apparent innocuousness and each drip as normal and conventional, or at least described to us as such by our leaders or the media. Those who do evil are quite convinced that they are the good guys in their story and those who observe evil work extraordinarily hard, for a number of reasons, both consciously and unconsciously, to portray it as normal rather than aberrant.
We are, however, what we do not what we say we do. While there are many shades of gray in human behavior, that does not mean that there is no black and no white. Evil done under claim of righteousness is still evil.
As Hannah Arendt so compellingly observed in Eichmann in Jerusalem: A Report on the Banality of Evil, Adolf Eichmann was an unremarkable man, not a mustache twirling villain. He told himself, every day, that what he was doing was fine because everyone around him acted as if it was fine, duly passing laws to validate his acts, obediently nodding their heads or turning their heads away as it was done. When he had misgivings about what he was doing he'd try to make up for it with a good act here or a good act there, telling himself that his balance sheet was, more or less in order. He did not believe he was evil because he never consciously chose to do evil as such and did not consider that there was a higher arbiter of morality than the people who passed the laws or gave him orders.
Morality does not work like that. We must examine that what we do and that which we support, vigilantly. We must ask ourselves more than "is what is happening legal?" or "is what is happening good for me?" We must ask, in broad terms, "is what I'm doing right, moral, ethical and just?" We must ask the same of our leaders and of that which is being done in our name.