Elizabeth's final statement is a testament to how much she has changed and how much her marriage to John has changed throughout the course of the play. From a point where she had difficulty understanding John and was distant from him, to pleading with him to sign a false confession, to fully understanding his motivations and why he must take the stand he does, she has become an almost transcendental figure by the end of it. The idea of her being able to fully grasp why John must do what she does is one that reflects how much she has changed and how much faith she has in him. At the start of the play, the affair with Abigail had cast its shadow in her lack of faith in him and the doubts that presented themselves in their marriage. Yet, in saying, "God forbid I take it from him," it is almost as if she understands his stance, John's need to make right what was wrong, and his need to stand for something in a society where no one does. It is at this point and the very idea that she would beg to God to make sure that she fully recognizes this higher sense of sacrifice that reflects her transformation into a paragon of virtue and nobility at the end of the play.
The last thing Elizabeth says is the last line of the play:
He have his goodness now. God forbid I take it from him.
Elizabeth knows this has been a terrible time for their marriage and personally for John. She is not a pregnant woman looking forward to a future without a man to help her, but she has recognized John's quest for righteousness throughout the play. He has wrestled with sin and tried to defeat it as every Puritan does. However, sin cannot be defeated by just crossing it out with rightous acts. Only God can forgive. As John takes this unearned punishment for the sin of witchcraft, he is in a sense a Christ character. The last thing Elizabeth would want to take from him is that role, and his own justification after he struggled through the sin of his own adultery.