This leads to St. John’s other important function: he provides an interesting comparison to the models of religion embodied in Helen Burns and Mr. Brocklehurst. Unlike the meek and forbearing Helen, St. John is active and even ambitious. He is not hypocritical like Brocklehurst, but he is so rigidly principled and lacking in empathy that his behavior is potentially just as destructive.
Despite Jane’s protracted attempt to integrate Christian morality comfortably into her own life and behavior, St. John is a dangerous influence on her, because his forceful personality compels her obedience against her own internal feelings. Jane refuses to marry St. John because she does not love him, but St. John pressures Jane to ignore her feelings and submit to his powerful conception of necessary moral duty. Jane remains true to herself only with great difficulty, and with the help of the preternatural experience of hearing Rochester call out her name over the moors. In declining St. John’s proposal Jane escapes yet another threat to her freedom and her sense of self.
Yet the very seriousness with which Jane considers his proposal leads her to an important realization about herself. Part of the reason she fled Thornfield was that she feared becoming a slave to her own passion and sacrificing her principles. By coming so close to marrying St. John, she demonstrates her ability to do the opposite: to sacrifice passion altogether and devote herself wholly to principle. Now Jane knows that returning to Rochester would not signify a weakness on her part. Moreover, she now appreciates more than ever what Rochester offered her. Having found herself on the threshold of a loveless marriage, she understands fully the importance of following not only her mind but also her heart.