In The Crucible Act 4, what idea is Judge Danforth trying to convey when he says, "Who weeps for these, weeps for corruption!"?

When Danforth says this line, he is essentially showing
that he is taking a very hard line against the people who have been accused of
witchcraft.  He is basically saying that all the people who have been accused are guilty
and are evil and corrupt (sinful).

At this point in the
play, many of the people (including Rev. Hale) have grave doubts about the trials.  They
feel that the trials are starting to convict innocent people.  This has come about
because well respected people like John Proctor and Rebecca Nurse are going to be
hanged.

But Danforth will admit no doubts.  He is going to
stand firm and maintain that all who are accused are evil
people.