Learn English – One word for witches and wizards

"Witchcraft Studies"

See for example "A Neglected Aspect of Witchcraft Studies", "Witchcraft studies in Austria, Germany and Switzerland" and "Witchcraft Studies from the Perspective of Women’s and Gender History: A Report on Recent Research".

The term has been used for the study of modern practices of witchcraft like Wicca, Feri, 1734, etc. for the study of earlier practices these have sometimes claimed to descend from (including a range of positions as to whether that is the case) for the beliefs of those who claimed that witches were attacking society (from the witch crazes of the early modern period and earlier through to the "Satanic Panic" of the 1980s and beyond) and to other practices of magic that have been given the label "witchcraft". It has also been used for historical, sociological, political and other analyses of witchcraft.

As such it fits your question very well.

It's wide enough that you may wish to be narrower as with something like "history of witchcraft" etc.

It also overlaps with "pagan studies", in that something covering modern pagan witchcraft like Hutton's Triumph of the Moon or Joanne Pearson's Wicca and the Christian Heritage would definitely be in the overlap, something like Margot Adler's Drawing Down the Moon would be more "pagan studies" than "witchcraft studies" as while it is certainly significant in the latter it covers much in the wider scope, and something like Levack's The Witch-Hunt in Early Modern Europe would be "witchcraft studies" but not directly concerned with "pagan studies" as it doesn't look at modern witchcraft practices at all and as such is only relevant to actual witchcraft practices and (by extension) paganism in so far as the period it studies has a cultural significance among modern witches.

It seems you want a word for someone refusing to engage in discussion, because they regard the subject as not open to debate. To dismiss out of hand is one option which has already been suggested, or more neutrally you might have to disengage from discussion.

In a similar vein I would suggest shut down debate.

I also detail how accusations of trolling were used as a justification for shutting down debates about community expectations ... — Bergstrom, Kelly. "'Don’t feed the troll': Shutting down debate about community expectations on Reddit.com". First Monday, Volume 16, Number 8.

In this quote, it is alleged that users refused to engage in discussion about community expectations and instead just "called troll", which is similar to your example where people "call out racism/sexism" rather than engaging.

I helped shut down an abortion debate between two men because my uterus isn't up for their discussion. — Title of an article by Niamh Mcintyre. The Independent, 18 November 2014.

Here the writer states that she prevented, rather than engaged in, a debate, because she felt the participants lacked relevant standing.

If you want give a more specific reason for the disengagement, rather than just acknowledge that the it occurred, you might like play the race card, or equivalently play the sexism card.

Playing the race card is an idiomatic phrase that refers to exploitation of either racist or anti-racist attitudes by accusing others of racism. — Wikipedia entry for "Race card", as of 3 July 2015.

An example usage from the British press:

Disgraced former mayor Lutfur Rahman (pictured) is said to have played the race card to silence opponents - and his deputy today reiterated claims there is deep seated racism in the borough of Tower Hamlets, in east London. — "Vote rigging party is STILL playing the racism card: Day after mayor is forced out, deputy blames 'Islamophobia'". Daily Mail, 25 April 2015.

And one from the States:

Democrats won't be able to play the sexism card if Republicans pit former Hewlett-Packard CEO Carly Fiorina against Democrat Hillary Clinton, says John Sununu ... — "John Sununu: Carly vs. Hillary Would End Dems' Phony Cries of Sexism". Newsmax, 31 March 2015

Both of these news sources are notoriously conservative: I don't think either card-playing idiom is very likely to be used by a political liberal or centrist except ironically! So these are less neutral terms than "shutting down debate" is.