Over and over, Danforth says that the good have nothing to fear. What evidence can you give to show that the opposite is true?

The evidence to go against this is pretty clear.  You can see that the statement is not true simply by looking at some of the people who get convicted and executed.

We know that Tituba, at least, sort of "deserves" to be executed because she was really trying to mess around with the supernatural.  But as far as we know, she's the only one who gets executed who actually did something.

By contrast, you have John Proctor executed (and Elizabeth would have been if she hadn't been pregnant).  You have Rebecca Nurse and Giles Corey.  None of them ever did anything wrong.

So their executions show that the good really do have something to fear.