what is the irony in the statement "So now theyand their church found it necessary to deny any other sect its freedom, lest their New Jerusalem be defiled and corrupted by wrong and deceitful ideas."

The clear irony here is the obvious disconnect between the "Christian" people of Salem and the Christ of the Gospels. Jesus made a habit of mingling with prostitutes, tax collectors, and even political terrorists. To attempt to keep the New Jerusalem from being "corrupted" is to completely misunderstand what the New Jerusalem is: namely, the hope of humankind's salvation brought about by Christ's life, death and resurrection.