Proctor's quote is an example of an allusion.  Given how people in the position of power have infused religious zeal as part of the accusation process in the Salem Witch Trials, Proctor's allusion is highly effective.

Proctor's allusion to the Bible is a critical moment in the drama.  Proctor is able to make the case that Hale's function as a part of the Salem leadership is akin to Pontius Pilate and his role in the death of Jesus Christ.  Pilate suggests that he can wash his hands of Jesus's death by placing the responsibility on the people.  Proctor's allusion insists that Hale will not be able to do the same.  He will not be able to remove his culpability in what is happening to people like Elizabeth Proctor and others who are being unfairly accused and sentenced.  

Proctor alludes to the Bible.  He wishes to make the case that what is happening in Salem is as unholy as Jesus being crucified.  The allusion is particularly effective because it connects innocent people being unjustly harassed to those in the position of power who wish to advance a specific agenda.  

In referencing the New Testament, Proctor is able to directly indict the "religious" nature of the trial proceedings.  Hale is a very religious man, but Proctor's insistence that he will not be able to wash his hands of what is being done forces him to reevaluate what he is doing. Proctor's allusion is also effective because it clearly draws a line between being right as opposed to merely doing right.