>> Many modern witches style themselves as goddess-worshippers, but in medieval and early modern witchcraft spells, the Virgin Mary plays a much bigger role. She is referenced far more often than any goddess. I believe the Virgin Mary is considered to be an aspect of the goddess, like other female deities and divine figures: Aphrodite, Ishtar, Freya, Bast, Kali, etc. In that sense, there is no incongruity.
Because Catholicism isn't really Christian before Trent. The whole point of the article is that magic was conjoined to Catholicism not opposed to it. Saints are small gods. What it doesnt discuss is the way Erasmus and Luther and Calvin and ultimately the church itself reformulated Christianity in the process starting the witch trials.