Witchcraft itself is not a religion. Rather, witchcraft is just what it says: a craft, and one that stands on its' own. There are religious witches from every religion. And there are irreligious witches, for whom deities play no part in their craft.
Strictly speaking, this guide is not only about witchcraft. It is intended as a newbie's guide for the most commonly found 'path' in North America: eclectic neo-pagan religious witchcraft. This path is sometimes mistakenly called 'Wicca', but bears little resemblance to Wicca outside of what it borrows from its' outer court and public rites. Wicca requires initiation into a lineaged coven, and is only properly practiced by a coven.