There are a few myths that I see surfacing in this thread. I'd like to take a moment to clear them up a bit.
Pagan is a very broad and rather generic term that covers a lot of different religions -- many people define it as any religion that is not Judaism, Islam, or Christianity.
Witchcraft is the use of magick for practical ends and has existed in pretty much all cultures, in all religious contexts, throughout history. There are witches who are Pagan, witches who are Jewish, witches who are Christian, and witches who are Muslim. There are also witches who are agnostic and witches who are atheist. Being a witch does not necessarily mean following a specific religion.
Wicca however is a religion. A lot of people mistakenly use the words witch and Wiccan as though they meant the same thing. Wicca does draw heavily from witch lore and practices (and it's usually said that all Wiccans are witches) but not all witches are Wiccans.
Most scholars today believe that the religion of Wicca started in the early part of the 20th century largely due to the work of Gerald Gardner in the UK. There were definitely witches before Gardner's time, but there is no convincing evidence to date which indicates Wicca predates Gardner. Ronald Hutton's "The Triumph of the Moon" is an often-recommended book detailing what historians know about the history of Wicca.
The Wiccan Rede, "An it harm none, do what you will," was only really embraced by Wiccans around the mid-1960s. Since then many Wiccans have taken the ethical statement as core to their beliefs, but there are other Wiccans who did not. The Wiccan Rede might be common among many Wiccans but it is not required nor is it universally accepted. And of course non-Wiccan witches can decide to adopt the idea or not as they choose.
Many Wiccans (myself included) interpret the Wiccan Rede to be a guideline which recommends we strive to cause the least harm possible. It's impossible to cause absolutely no harm, as even by breathing our bodies kill off microorganisms in the air. Instead we attempt to be aware of the possible consequences of our decisions and seek the path which causes least harm all around. Sometimes though we do have to cause clear harm in order to lessen harm on a greater scale. In any case, we must accept responsiblity for the consequences of our actions.
The Wiccan Rede is an idea and I seriously doubt that you can harm an idea. You can misunderstand an idea, or decide to reject an idea, but the idea does not have feelings that can be hurt and the idea itself can't be damaged (although promoting variations of it can result in the evolution of the idea.)
; )
Ben Gruagach