As a historian of religion, I maintain the position that it is essential to be empathetic toward that which we study, but not sympathetic. Sympathy is defined as "fellow feeling," it is the sharing of emotion, interest, and desire. sun is Greek for "together with" while pathos is Greek for "feeling."
Empathy is defined as "intellectual" understanding, it is an appreciation of the Other without being the Other. en is Greek for "in" while pathos is Greek for "feeling."
Sympathy means that one shares his/her identity with those being studied. The researcher is emotionally connected to his/her subject, and therefore unable to maintain enough of a distance from the subject to be able to critically study it. Sympathy also causes trouble for the researcher when s/he wishes to study the Other, because the Other looks very different. When this happens, the Other often is characterized by the researcher as bad, evil, silly, scary, even crazy. Why? Because his/her sympathy for the one thing makes it difficult to understand the Other without doing so in terms of the heretic, the lunatic, or the devil.
Too often this is how the study of Gnosticism is approached by those in the Academy. I can not tell you the number of times scholars have come up to me and said, "Oh you study those crazy texts." "Why do you bother? They were loonies anyway." Or how often Gnosticism is characterized in writing as totally foreign, heretical, that they thought the body is totally negative and that this world is a nasty place. First this is a caricature of the Gnostics; it is not what they actually say. Second the same caricature can be made of the early apostolic or mainstream Christians who for the most part hated the body and sex, and tried to escape the fate of the world and its demons through baptism. Hence the strong traditions of martyrdom and erasure of the body (have you ever really read Ignatius' letter to the Romans?) and monasticism (the deprived and starved body was the exalted heavenly body!). I could go on at length, but won't given the need for brevity in blogs.
Empathy, however, allows the researcher to appreciate his/her subject, in an attempt to understand the subject for the subject's sake. There is an attempt to try to figure out how the subject works from the outside in. The goal is to understand the subject fairly, without personally becoming the subject. This means for the Gnostics that they are treated with respect, their positions are mapped as accurately as they can be, so that their voices can become part of the conversation that was early Christianity. Once this is done, we will learn a lot more than we now know. The inclusion of their voices will benefit the whole. But this can only be accomplished with empathy.