Atheists ARE Pagans
Just to make it clear...
Even if the "witch" was Atheist, by the prevailing lexicon of the time, she would have been labeled a Pagan.
The term "Pagan" was nothing more than a racist slur to call backwards people. It's like calling people "Hicks." Hicks can be Christian, Jewish, Atheist, it doesn't matter. If they are backwards people who still drink moonshine and are pissed off about losing the Civil War, they are Hicks.
And yes, even in modern times, Atheists ARE Pagans, but not all Pagans are Atheists.
Take this for example: Most Atheists in the United States celebrate traditionally Pagan holidays like Easter, Halloween, and the Winter Solstice. Also, most Atheists even have a "Tree of Life" in their living rooms during the Winter Solstice in which gifts are placed under.
Atheists go out of their way to celebrate Pagan holidays. Technically, I guess the true term would be Atheist/Pagan. They are not fully Atheist, but yet, they don't believe in any of the Pagan gods but still partake in Pagan celebrations.