Well, actually, it's Christianity that's against Witchcraft, not the other way around. It's the Christians that think Witchcraft is "devil worship". As for the meaning that shows up the most, the triquetra is an ancient symbol, that has been used for hundred of years. The reason for the current Wiccan popularity of the symbol, could quite possibly be because of Charmed. Many people who would have overlooked the symbol before, found themselves adopting it from their favorite show. Certainly, the creators of Charmed did their research, and wanted a symbol that would represent the Power of Three. And what better symbol then the Triquetra? Since it does represent "the trinity"... There are many different trinities. Yes, it can represent the Christian "Father/Son/Holy Spirit" trinity, but it also represents the Wiccan "Virgin/Mother/Hag" trinity. Many different religions have adapted it to represent their own trinities, but those are the two most common known trinities.... (At least to me! ) Though the Triquetra's roots are firmly in the Pagan/Wiccan arena...

Yeah, I thought of that after (the triquetra being a Celtic symbol). Sometimes I start to ramble, and forget little pieces of information... Sorry... lol And in my own defence, Celtic symbols and Paganism are usually intertwined, aren't they?... Kind of like Christianity is comprised of Catholics, Anglicans, Protestants, and so on. Paganism is comprised of Wiccans, Druids, and other such religious... And now we are slipping off-topic a little... Oops... lol