The first comment I would have to make in regards to this statement has to do with the entire community. What was the Puritan community doing while people they knew to be innocent were being hung? That they tolerated it and did nothing, this in itself defines indifference to evil.
John is a hypocrite, he is prideful, but he is also an intrinsically good man. There is never a point during the course of the novel that he does not question the evil that permeates the town, but he does take his time in coming forward....... because of his own guilt and knowledge of wrong doing. When Elizabeth is arrested, he can no longer justify his own silence. By speaking, he regains his integrity. His refusal to sign a confession seals his fate, but he knew that to sign anything would have added to the evil. This was how he acted on his beliefs. In order to fight the evil, he knew he couldn't be indifferent to it. He gave his life to help end it.