Her two most influential books were:
Murray's view of a powerful, universal, European underground religion included charismatic renderings of Joan of Arc, King William Rufus, etc. as sacrificial leaders. Her ideas brought her considerable scholarly disapproval in an academia still largely dominated by Church ethos.
It is usually agreed that her vision was greatly overstated, some dismiss it completely. A sceptical view of her theories, prioritising examples of her selective quoting of texts to support her thesis, can be found in Norman Cohn's book, Europe's Inner Demons; (ISBN 0226113078) However Norman Cohn was very mistaken in his allegations. He alleged that specific texts were omitted by Murray as they would have discredited her sources, the testimonies of people put on trial for witchcraft in the Early Modern Period. But on checking it turned out that she had not omitted these texts and had been falsely discredited. But many historians, such as Ronald Hutton, did not check and Murray was wrongly widely discredited. She may have made other errors, but she did not make the errors that Cohn accused her of.
In a more sympathetic reading, a considerable patchwork of Pagan survivals can be seen throughout European history, and Murray's work did much to alert attention to this previously concealed history of European religion. Isolated individuals or groups certainly did practice Pagan customs and rituals that were not part of ordinary Christian dogma, as signs of such beliefs can be seen in Church architecture and local legends. However such practitioners typically saw themselves as Christian, though radical (see Hutton, UK). The existence of an effective underground resistance movement to the Church seems unlikely as its political hegemony was profound, ie the Church worldview was so established as to leave virtually no room for another set of ideas, so its principles were completely taken for granted as 'reality.'
Some local organisation at times is feasible to support heretics and witches, perhaps smuggling the means of suicide to the condemned. There is evidence that bribes could procure a more merciful execution by burning to use green wood that suffocated its victims, but such bribery could arise naturally through the intersection of greedy guards and concerned relatives without the mediation of any underground organisation.
Murray's chosen historical figures such as Joan of Arc and William Rufus have received wildly different interpretations by different interest groups through the centuries. Her own portrait of messianic (self) sacrifices can be included as part of our understanding of such contested personalities, but must be set alongside other contributions, including that of secular economics and psychological aberration.