What I particularly admire in him is the firm stand he has taken, not only against the oppressors of his countrymen, but also against those opportunists who are always ready to compromise with the Devil. He perceives very clearly that the world is in greater peril from those who tolerate or encourage evil than from those who actually commit it.
Notes from Wikiquote
The world is a dangerous place to live, not because of the people who are evil, but because of the people who don't do anything about it. | As quoted in The Harper Book of Quotations by Robert I. Fitzhenry (1993), p. 356 | The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing. | As quoted in Conscious Courage : Turning Everyday Challenges Into Opportunities (2004) by Maureen Stearns, p. 99 | The world will not be destroyed by those who do evil, but by those who watch them without doing anything.
Variants
s or paraphrasing